Liquid crystal display apparatus having alignment control for brightness and response

ABSTRACT

A liquid crystal display apparatus including a pair of substrates having electrodes and vertical alignment layers. A liquid crystal having a negative anisotropy of dielectric is inserted between the substrates. Each substrate has linearly arranged alignment control structures for controlling the alignment of the liquid crystal. The alignment control structures are formed in the form of projections or slits. Each alignment control structure is formed of a plurality of constituent units. In addition, means for forming a boundary of alignment of liquid crystal (singular point in director field) to control the liquid crystal located on the alignment control structures.

This is a Divisional of application Ser. No. 12/783,362, filed May 19,2010, which is a Continuation of application Ser. No. 12/533,825, filedJul. 31, 2009, which is a Continuation of application Ser. No.11/977,358, filed Oct. 24, 2007, now U.S. Pat. No. 7,593,081, which is aDivisional of application Ser. No. 11/390,727 filed Mar. 28, 2006, nowU.S. Pat. No. 7,321,412, which is a Continuation of application Ser. No.09/398,126 filed Sep. 16, 1999, now U.S. Pat. No. 7,405,789.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display apparatus suchas a TV set or a display. In particular, the present invention relatesto a liquid crystal display apparatus including a vertically alignedliquid crystal.

2. Description of the Related Art

A liquid crystal display apparatus includes a liquid crystal insertedbetween a pair of substrates. The pair of substrates include electrodesand alignment layers, respectively. The TN liquid crystal displayapparatus that finds wide applications includes horizontal alignmentlayers and a crystal having a positive anisotropy of its dielectricconstant when no voltage is applied, the liquid crystal is alignedsubstantially parallel to the horizontal alignment layers. When avoltage is applied thereto, on the other hand, the liquid crystalbecomes substantially perpendicular to the horizontal alignment layers.

The TN liquid crystal display apparatus has the advantage that it can bemade thin but has the disadvantage that the visual field angle is small.A method of improving this disadvantage and assuring a wide visual fieldangle is alignment division. In alignment division, each pixel isdivided into two regions, so that the liquid crystal rises toward oneside in one region and rises toward the opposite side in the otherregion. In this way, a wider visual field angle is assured by averagingthe behavior of the liquid crystal in one pixel.

To control alignment of the liquid crystal, the alignment layers arenormally rubbed. For alignment division, one region of the pixel isrubbed in a first direction using a mask, and the other region of theone pixel is rubbed in a second direction opposite to the firstdirection using a complementary mask. As an alternative, the wholealignment layer is rubbed in the first direction, and the one region orthe other region of one pixel is selectively irradiated with ultravioletrays using a mask thereby to create a pretilt difference between the oneregion and the other region.

In a liquid crystal display apparatus using horizontal alignment layers,it is necessary to carry out cleaning to clean the substrates formedhaving the alignment layers after rubbing. As a result, the fabricationof the liquid crystal panel is comparatively troublesome and thesubstrates may be polluted during the rubbing.

In a liquid crystal display apparatus using vertical alignment layers,on the other hand, the liquid crystal is aligned substantiallyperpendicular to the vertical alignment layers when no voltage isapplied thereto and the liquid crystal is substantially parallel to thevertical alignment layers when a voltage is applied thereto. Also with aliquid crystal apparatus using the vertical alignment layers, thealignment layers are normally rubbed for controlling the alignment ofthe liquid crystal.

Japanese Unexamined Patent Application No. 10-185836 filed by theassignee of this application proposes a liquid crystal display apparatuscapable of controlling alignment of the liquid crystal, without rubbing.This liquid crystal display apparatus is an aligned crystal displayapparatus of a vertical alignment type, includes a liquid crystal havingvertical alignment layers and a negative anisotropy of dielectricconstant, and has alignment control structures (linearly arrangedstructures having projections or slits) on each of the pair ofsubstrates for controlling the alignment of the liquid crystal.

This liquid crystal display apparatus of a vertical alignment type hasthe advantages that no rubbing is required and that the alignmentdivision can be attained by the arrangement of the linearly arrangedstructures. With this liquid crystal display apparatus of a verticalalignment type, therefore, it is possible to secure a wide visual fieldangle and a high contrast. Elimination of the requirement of rubbingallows the cleaning after rubbing to be eliminated. Thus, thefabrication of a liquid crystal display apparatus is facilitated, andwithout any pollution on the substrates, which otherwise might occur atthe time of rubbing, the reliability of the liquid crystal displayapparatus is improved.

In the liquid crystal display apparatus of a vertical alignment typehaving alignment control structures (projections or a slits) onsubstrates for controlling alignment of the liquid crystal, it has beenfound that there are regions where the alignment of liquid crystalmolecules is unstable, and there are problems regarding brightness andresponse speed, which must be improved.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a liquid crystaldisplay apparatus of a vertical alignment type which has improvedbrightness and response.

A liquid crystal display apparatus according to the present inventioncomprises a pair of substrates having electrodes and vertical alignmentlayers, a liquid crystal having a negative anisotropy of its dielectricconstant inserted between the pair of substrates, and alignment controlstructures arranged in each of the pair of substrates for controllingthe orientation of the liquid crystal. Each alignment control structurecomprises a plurality of constituent units.

With this configuration, each alignment control structure comprises aplurality of constituent units, so the movement of different alignmentregions is smaller at the time of voltage application and the movementis rapidly ended. As a result, it is possible to provide a liquidcrystal display apparatus having a high brightness and a high responsespeed.

According to another aspect of the invention, there is provided a liquidcrystal display apparatus comprising a pair of substrates havingelectrodes and vertical alignment layers, a liquid crystal having anegative anisotropy of its dielectric constant inserted between the pairof substrates, and alignment control structures arranged in each of thepair of substrates for controlling alignment of the liquid crystal. Thealignment control structures of at least one of the substrates has meansfor forming a boundary of alignment of a first type in which the liquidcrystal molecules around a point are directed to said point and meansfor forming boundary of orientation of a second type in which a part ofthe liquid crystal molecules around a point are directed to said pointand the other liquid crystal molecules around said point are directedaway from said point.

According to still another aspect of the invention, there is provided aliquid crystal display apparatus comprising a pair of substrates havingelectrodes and vertical alignment layers, a liquid crystal having anegative anisotropy of its dielectric constant inserted between the pairof substrates, and alignment control structures arranged in each of thepair of substrates for controlling alignment of the liquid crystal. Thealignment control structures of one substrate are shifted from thealignment control structures of the other substrate, as viewed in thedirection normal to the one substrate, and each of one substrate and theother substrate includes means for forming a boundary of alignment ofliquid crystal molecules at fixed positions with respect to thealignment control structures of the opposed substrate, at the time ofvoltage application thereto.

According to a further aspect of the invention, there is provided aliquid crystal display apparatus comprising a pair of substrates havingelectrodes and vertical alignment layers, a liquid crystal having anegative anisotropy of its dielectric constant inserted between the pairof substrates, and alignment control structures arranged in each of thepair of substrates for controlling alignment of the liquid crystal. Eachalignment control structure comprises a plurality of constituent units,and the constituent units of the alignment control structures of onesubstrate and the constituent units of the alignment control structuresof the other substrate are arranged alternately on one line, as viewedin the direction normal to one substrate.

According to a still further aspect of the invention, there is provideda liquid crystal display apparatus comprising a pair of substrateshaving electrodes and vertical alignment layers, a liquid crystal havinga negative anisotropy of its dielectric constant inserted between thepair of substrates, and alignment control structures arranged in each ofthe pair of substrates for controlling alignment of the liquid crystal.Each alignment control structure has a bent portion, and an additionalalignment control structure is formed on the obtuse angle side of thebent portion of the alignment control structure of the substrate havingthe alignment control structures.

According to a yet further aspect of the invention, there is provided aliquid crystal display apparatus comprising a pair of substrates havingelectrodes and vertical alignment layers, a liquid crystal having anegative anisotropy of its dielectric constant inserted between the pairof substrates, and alignment control structures arranged in each of thepair of substrates for controlling alignment of the liquid crystal. Thealignment control structure has a bent portion and an additionalalignment control structure is arranged on the acute angle side of thebent portion of the alignment control structure of the substrate opposedto the substrate having the alignment control structures.

According to a still further aspect of the invention, there is provideda liquid crystal display apparatus comprising a pair of substrateshaving electrodes and vertical alignment layers, a liquid crystal havinga negative anisotropy of its dielectric constant inserted between thepair of substrates, linearly arranged structures arranged in each of thepair of substrates for controlling alignment of the liquid crystal, andpolarizers arranged respectively on the outside of the pair ofsubstrates. One polarizer has an absorption axis displaced by apredetermined angle from an orientation rotated 45 degrees with respectto an orientation where the linearly arranged structures extend.

With this configuration, brightness of the liquid crystal displayapparatus can be improved. Preferably, assuming that the crossing anglebetween the orientation of the absorption axis of the one polarizer andthe linearly arranged structures is a, the crossing angle a is adaptedto satisfy the relationship, 25°<a<43° or 47°<a<65°.

According to a further aspect of the invention, there is provided aliquid crystal display apparatus comprising a pair of substrates havingelectrodes and vertical alignment layers, a liquid crystal having anegative anisotropy of its dielectric constant inserted between the pairof substrates, and alignment control structures arranged in each of thepair of substrates for controlling alignment of the liquid crystal. Atleast one substrate has TFTs connected to electrodes, shielding areasare arranged to cover the TFTs and the areas in the neighborhoodthereof, and the shielding areas are overlapped partially with a part ofthe alignment control structures so that the area of the alignmentcontrol structures arranged in non-shielding areas is reduced.

With this configuration, brightness of the liquid crystal displayapparatus can be improved. Preferably, in the case where the alignmentcontrol structures of the substrate having the TFTs are slits, thealignment control structures of the other substrate are overlapped withthe shielding areas covering the TFTs.

According to yet another aspect of the invention, there is provided aliquid crystal display apparatus comprising a pair of substrates havingelectrodes and vertical alignment layers, a liquid crystal having anegative anisotropy of its dielectric constant inserted between the pairof substrates, and a linearly arranged structures arranged in each ofthe pair of substrates for controlling alignment of the liquid crystal.There are further provided first means arranged in the linearly arrangedstructures of one substrate for forming a boundary of alignment of theliquid crystal, and second means arranged on the other substrate at thesame position as that of the first means in the direction in which thelinearly arranged structures extend.

With this configuration, the orientation of the liquid crystal can befurther assured for forming a boundary of alignment of the liquidcrystal.

According to a yet further aspect of the invention, there is provided aliquid crystal display apparatus comprising a pair of substrates havingelectrodes and vertical alignment layers, a liquid crystal having anegative anisotropy of its dielectric constant inserted between the pairof substrates, and linearly arranged structures arranged in each of thepair of substrates for controlling alignment of the liquid crystal. Thelinearly arranged structures of the one substrate are formed in such amanner that at least the liquid crystal molecules located at a firstposition are aligned in the first direction parallel to the linearlyarranged structures upon application of a voltage thereto, the linearlyarranged structures of the other substrate are formed in such a mannerthat at least the liquid crystal molecules located at the secondposition on the linearly arranged structures are aligned in the seconddirection opposite to the first direction in parallel to the linearlyarranged structures upon application of a voltage thereto, and the firstposition and the second position are located on a line perpendicular tothe linearly arranged structures.

With this configuration, the trace appearing in the display when theliquid crystal display apparatus is affected by an external pressure canbe eliminated. Preferably, the linearly arranged structures of the onesubstrate and the linearly arranged structures of the other substrateboth include means for forming a boundary of alignment of a first typewith the liquid crystal molecules around a point directed to said point.As an alternative, the linearly arranged structures of the one substrateand the linearly arranged structures of the other substrate may bothinclude means for forming a boundary of alignment of a second type withthe liquid crystal molecules around a point partially directed to saidpoint and the other liquid crystal molecules are directed away from thesame point.

According to still another aspect of the invention, there is provided aliquid crystal display apparatus comprising a pair of substrates havingelectrodes and vertical alignment layers, a liquid crystal having anegative anisotropy of its dielectric constant inserted between the pairof substrates, alignment control structures arranged in each of the pairof substrates for controlling alignment of the liquid crystal, and anauxiliary wall structure on at least one of the substrates between thealignment control structures of the substrate pair, as viewed in thedirection normal to the substrate pair.

With this configuration, the response to the voltage application can beimproved. Preferably, the auxiliary wall structure is long in thedirection perpendicular to the alignment control structures and isarranged at a predetermined pitch along the alignment controlstructures.

According to a yet further aspect of the invention, there is provided aliquid crystal display apparatus comprising a pair of substrates havingelectrodes and vertical alignment layers, a liquid crystal having anegative anisotropy of its dielectric constant inserted between the pairof substrates, alignment control structures arranged in each of the pairof substrates for controlling alignment of the liquid crystal, andliquid crystal inclined orientation control means arranged between thealignment control structures of the substrate pair ill which a parameterchanges in one direction from one of the alignment control structures.

With this configuration, response to the voltage application can beimproved.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more apparent from the followingdescription of the preferred embodiments, with reference to theaccompanying drawings, in which:

FIG. 1 is a schematic cross-sectional view showing a liquid crystaldisplay apparatus;

FIG. 2 is a schematic cross-sectional view showing a vertical alignmenttype liquid crystal display apparatus having alignment controlstructures for controlling alignment of the liquid crystal;

FIG. 3 is a plan view showing one pixel and the alignment controlstructures;

FIG. 4A is a plan view of the linearly arranged structures of FIGS. 2and 3 with liquid crystal molecules falling based on the linearlyarranged structures at the time of voltage application;

FIG. 4B is a cross-sectional view taken along the line IVB-IVB in FIG.4A;

FIG. 5 is a plan view showing another example of the alignment controlstructures;

FIG. 6 is a schematic cross-sectional view showing a liquid crystaldisplay apparatus in which the alignment control structures of a pair ofthe substrates are both projections;

FIG. 7 is a schematic cross-sectional view showing a liquid crystalapparatus in which the alignment control structures of one substrate areprojections and the alignment control structures of the other substrateare slit structures;

FIG. 8 is a schematic cross-sectional view showing a liquid crystaldisplay apparatus in which the alignment control structures of a pair ofsubstrates are both slit structures;

FIG. 9 is a cross-sectional view showing an example of the alignmentcontrol structures in the form of projections;

FIG. 10 is a cross-sectional view showing an example of the alignmentcontrol structure in the form of slit structures;

FIG. 11 is a view explaining a problem of the alignment of the liquidcrystal display apparatus having alignment control structures;

FIG. 12 is a view showing the transmittance in several areas of FIG. 11;

FIG. 13 is a view showing an overshoot of brightness;

FIG. 14 is a view showing alignment control structures according to thefirst embodiment of the present invention;

FIG. 15 is a view showing a modification of the alignment controlstructures;

FIG. 16 is a view showing a modification of the alignment controlstructures;

FIG. 17 is a view showing a modification of the alignment controlstructures;

FIG. 18 is a view showing a modification of the alignment controlstructures;

FIG. 19 is a view showing a modification of the alignment controlstructures;

FIG. 20 is a view showing a modification of the alignment controlstructures;

FIG. 21 is a view showing a modification of the alignment controlstructures;

FIG. 22 is a view showing the pixel electrode and the slit structure ofFIG. 21;

FIGS. 23A to 23E are views explaining the formation of the alignmentcontrol structure in the form of projections;

FIG. 24 is a view showing the alignment of the liquid crystal of theliquid crystal display apparatus having the alignment controlstructures;

FIG. 25 is a view showing a display characteristic in the configurationof FIG. 24;

FIG. 26 is a view showing the alignment of the liquid crystal of theliquid crystal display apparatus having the alignment control structuresincluding a plurality of constituent units;

FIG. 27 is a view showing a display characteristic in the configurationof FIG. 26;

FIG. 28 is a view showing the alignment of the liquid crystal in theliquid crystal display apparatus having alignment control structuresaccording to the second embodiment of the present invention;

FIG. 29 is a view showing a display characteristic in the configurationof FIG. 28;

FIG. 30 is a view showing the feature of a boundary of alignment of afirst type and the feature of a boundary of alignment of a second type;

FIG. 31 is a plan view showing a specific example of the alignmentcontrol structures of FIG. 28;

FIG. 32 is a cross-sectional view through the alignment controlstructures of FIG. 31;

FIG. 33 is a plan view showing a modification of the alignment controlstructures;

FIG. 34 is a cross-sectional view through the structures of FIG. 33;

FIGS. 35A and 35B are plan views showing modifications of the alignmentcontrol structures;

FIG. 36 is a plan view showing a modification of the alignment controlstructures;

FIG. 37 is a plan view showing a modification of the alignment controlstructures;

FIGS. 38A and 38B are cross-sectional views of a portion of a liquidcrystal display apparatus near the edge of the pixel electrode;

FIGS. 39A and 39B are views showing the alignment of the liquid crystalat the edge of the pixel electrode of FIGS. 8A and 38B;

FIG. 40 is plan view showing a modification of the alignment controlstructures;

FIG. 41 is a plan view showing a modification of the alignment controlstructures;

FIG. 42 is a plan view showing a modification of the alignment controlstructures;

FIG. 43 is a plan view showing the alignment control structuresaccording to the third embodiment of the present invention;

FIG. 44 is a cross-sectional view of the liquid crystal displayapparatus passing through the alignment control structures of FIG. 43;

FIG. 45 is a view showing the alignment of the liquid crystal in theneighborhood of the alignment control structures of FIG. 44;

FIG. 46 is a view showing the alignment of the liquid crystal in theneighborhood of the alignment control structures according to the firstembodiment;

FIG. 47A is a cross-sectional view showing a modification of the meansfor controlling the boundary and the alignment control structures;

FIG. 47B is a schematic perspective view of FIG. 47A;

FIG. 47C is a schematic plan view of FIG. 47B;

FIG. 48 is a cross-sectional view showing a modification of the meansfor controlling the alignment in the boundary and the alignment controlstructures;

FIG. 49 is a cross-sectional view showing a modification of the meansfor controlling the alignment in the boundary and the alignment controlstructures;

FIG. 50 is a cross-sectional view showing a modification of the meansfor controlling the alignment in the boundary and the alignment controlstructures;

FIG. 51 is a plan view showing a modification of the means forcontrolling the alignment in the boundary and the alignment controlstructures;

FIG. 52 is a cross-sectional view taken along line 52-52 in FIG. 51;

FIG. 53 is a cross-sectional view taken along the line 53-53 in FIG. 51;

FIG. 54 is a plan view showing a modification of the means forcontrolling the alignment in the boundary and the alignment controlstructures;

FIG. 55 is a cross-sectional view of the liquid crystal displayapparatus through the alignment control structures of FIG. 54;

FIG. 56 is a plan view showing a modification of the means forcontrolling the alignment in the boundary and the alignment controlstructures;

FIG. 57 is a cross-sectional view of the liquid crystal displayapparatus through the alignment control structures of FIG. 56;

FIG. 58 is a plan view showing the alignment control structuresaccording to the fourth embodiment;

FIG. 59 is a schematic cross-sectional view of the liquid crystaldisplay apparatus taken along the line 59-59 of FIG. 58;

FIG. 60 is a plan view showing a modification of the alignment controlstructures;

FIG. 61 is a plan view showing a pixel electrode having the slitstructure of FIG. 60;

FIG. 62 is a plan view showing a modification of the alignment controlstructures;

FIG. 63 is a plan view showing a modification of the alignment controlstructures;

FIG. 64 is a plan view showing a modification of the alignment controlstructures;

FIG. 65 is a plan view showing a modification of the alignment controlstructures;

FIG. 66 is a plan view showing the alignment control structuresaccording to the fifth embodiment of the present invention;

FIG. 67 is a plan view showing a typical example of the alignmentcontrol structures having bent portions;

FIG. 68 is a view explaining the problem of the liquid crystal displayapparatus having the alignment control structures of FIG. 67;

FIG. 69 is a plan view showing a modification of the alignment controlstructures;

FIG. 70 is a plan view showing a modification of the alignment controlstructures;

FIG. 71 is a plan view showing a modification of the alignment controlstructures;

FIG. 72 is a plan view showing a modification of the alignment controlstructures;

FIG. 73 is a plan view showing a modification of the alignment controlstructures;

FIG. 74 is a plan view showing a modification of the alignment controlstructures;

FIG. 75 is a view showing the relationship between the alignment controlstructures and the polarizers of the liquid crystal display apparatusaccording to the sixth embodiment of the present invention;

FIGS. 76A to 76C are views showing the display brightness in theconfiguration of FIG. 75;

FIG. 77 is a view showing the relationship between the angle of thedirector of the liquid crystal and frequency thereof for minor areas inthe liquid crystal display apparatus having the alignment controlstructures for controlling the alignment of the liquid crystal;

FIG. 78 is a view showing the relationship between the alignment controlstructures and the polarizers of the liquid crystal display apparatusaccording to a modification of the embodiment of FIG. 75;

FIG. 79 is a cross-sectional view of the liquid crystal displayapparatus of FIG. 78;

FIG. 80 is a view showing the relationship between the alignment controlstructures and the polarizers of the liquid crystal display apparatusaccording to a modification of the embodiment of FIG. 75;

FIG. 81 is a cross-sectional view of the liquid crystal displayapparatus of FIG. 80;

FIG. 82 is a view showing the alignment control structures of a liquidcrystal display apparatus according to the seventh embodiment of thepresent invention;

FIG. 83 is a cross-sectional view taken along the line 83-83 in theliquid crystal display apparatus of FIG. 82;

FIG. 84 is a view showing a more specific example of the alignmentcontrol structures of FIG. 82;

FIG. 85 is a plan view showing a comparative example of the alignmentcontrol structures of FIG. 82;

FIG. 86 is a view showing a modification of the alignment controlstructures of FIG. 28;

FIG. 87 is a cross-sectional view taken along the line 87-87 of theliquid crystal display apparatus having the alignment control structuresof FIG. 86;

FIG. 88 is a view showing the alignment control structures of the liquidcrystal display apparatus according to the eighth embodiment of thepresent invention;

FIG. 89 is a cross-sectional view taken along the line 89-89 of a liquidcrystal display apparatus having the linear wall structure of FIG. 88;

FIG. 90 is a view showing a modification of the alignment controlstructures of FIG. 88;

FIG. 91 is a cross-sectional view through the liquid crystal displayapparatus having the alignment control structures of FIG. 89;

FIG. 92 is a view showing a modification of the alignment controlstructures of FIG. 88;

FIG. 93 is a cross-sectional view of the alignment control structures ofFIG. 92;

FIG. 94 is a view showing a modification of the alignment controlstructures of FIG. 93;

FIG. 95 is a view showing a modification of the alignment controlstructures of FIG. 88;

FIG. 96 is a cross-sectional view passing through the liquid crystaldisplay apparatus having the alignment control structures of FIG. 95;

FIG. 97 is a view showing a modification of the alignment controlstructures of FIG. 88;

FIG. 98 is a view showing a modification of the alignment controlstructures of FIG. 88;

FIG. 99 is a view showing the alignment control structures of the liquidcrystal display apparatus according to the ninth embodiment of thepresent invention;

FIG. 100 is a view showing a modification of the alignment controlstructures of FIG. 99;

FIG. 101 is a view explaining the problem of pressing, byfinger-pressure, the liquid crystal display apparatus having thealignment control structure;

FIG. 102 is a view showing an example liable to pose a problem whenpressed by a finger;

FIG. 103 is a view showing an example of means for forming boundary offirst type of FIG. 99;

FIG. 104 is a perspective view illustrating the liquid crystal displayapparatus having means for forming a boundary of first type of FIG. 103;

FIG. 105 is a view showing an example of means for forming a boundary ofsecond type of FIG. 99;

FIG. 106 is a perspective view illustrating the liquid crystal displayapparatus having means for forming a boundary of second type of FIG.105;

FIG. 107 is a view showing an example of means for forming a boundary offirst type of FIG. 99;

FIG. 108 is a view showing an example of means for forming a boundary ofsecond type of FIG. 99;

FIG. 109 is a view showing the alignment control structures of theliquid crystal display apparatus according to the tenth embodiment ofthe present invention;

FIG. 110 is a cross-sectional view taken along the line 110-110 of theliquid crystal display apparatus of FIG. 109;

FIG. 111 is a view showing a modification of the liquid crystal displayapparatus of FIG. 109;

FIG. 112 is a view showing a modification of the liquid crystal displayapparatus of FIG. 109;

FIG. 113 is a cross-sectional view taken along the line 113-113 of theliquid crystal display apparatus of FIG. 112;

FIG. 114 is a view showing a modification of the liquid crystal displayapparatus of FIG. 109;

FIG. 115 is a cross-sectional view taken along the line 115-115 of theliquid crystal display apparatus of FIG. 114;

FIGS. 116A to 116G are views showing a method of fabricating a substratehaving the alignment control structures and auxiliary wall structures;

FIGS. 117A to 117E are views showing another example of the method offabricating a substrate having the alignment control structures andauxiliary wall structures;

FIG. 118 is a view showing a response when the distance between theauxiliary structures (slits) is changed while fixing the width of theauxiliary wall structures (slits) in the liquid crystal displayapparatus of FIG. 111;

FIG. 119 is a view showing a response when the width of the auxiliarystructures (slits) is changed while fixing the distance between theauxiliary wall structures (slits) in the liquid crystal displayapparatus of FIG. 111;

FIG. 120 is a view showing a response when the distance between theauxiliary structures (slits) is changed while fixing the size of theauxiliary wall structures (slits) in the liquid crystal displayapparatus of FIG. 112;

FIG. 121 is a view showing a response with the size of the auxiliarystructures (projections) is changed while fixing the distance betweenthe auxiliary wall structures (projections) in the liquid crystaldisplay apparatus of FIG. 112;

FIG. 122 is a view showing the alignment control structures of theliquid crystal display apparatus according to the eleventh embodiment ofthe present invention;

FIG. 123 is a view showing a modification of the liquid crystal displayapparatus of FIG. 122;

FIGS. 124A to 124E are views showing a method of fabricating the liquidcrystal display apparatus of FIG. 122;

FIGS. 125A to 125E are views showing a method of fabricating the liquidcrystal display apparatus of FIG. 123;

FIG. 126 is a view showing a modification of the liquid crystal displayapparatus of FIG. 122;

FIG. 127 is a view showing a modification of the liquid crystal displayapparatus of FIG. 122;

FIG. 128 is a view showing a modification of the liquid crystal displayapparatus of FIG. 122;

FIG. 129 is a view showing a modification of the liquid crystal displayapparatus of FIG. 122;

FIG. 130 is a view showing a modification of the liquid crystal displayapparatus of FIG. 122;

FIG. 131 is a view showing a modification of the liquid crystal displayapparatus of FIG. 122;

FIG. 132 is a view showing a modification of the liquid crystal displayapparatus of FIG. 122;

FIGS. 133A to 133C are views showing modifications of the liquid crystaldisplay apparatus of FIG. 122;

FIGS. 134A to 134C are views showing modifications of the liquid crystaldisplay apparatus of FIG. 122;

FIGS. 135A and 135B are views showing a modification of the alignmentcontrol structures of FIG. 43;

FIGS. 136A and 136B are views showing a modification of the alignmentcontrol structures of FIG. 43;

FIGS. 137A and 137B are views showing a modification of the alignmentcontrol structures of FIG. 43;

FIGS. 138A to 138E are views showing a modification of the alignmentcontrol structures of FIG. 43;

FIGS. 139A and 139B are views showing a modification of the alignmentcontrol structures of FIG. 43;

FIGS. 140A and 140B are views showing a modification of the alignmentcontrol structures of FIG. 43;

FIGS. 141A to 141D are views showing a modification of the alignmentcontrol structures of FIG. 43;

FIGS. 142A to 142D are views showing a modification of the alignmentcontrol structures of FIG. 43;

FIGS. 143A to 143D are views showing a modification of the alignmentcontrol structures of FIG. 43;

FIGS. 144A and 144B are views showing a modification of the alignmentcontrol structures of FIG. 43;

FIGS. 145A and 145B are views showing a modification of the alignmentcontrol structures of FIG. 43;

FIGS. 146A to 146D are views showing a modification of the alignmentcontrol structures of FIG. 43;

FIGS. 147A and 147B are views showing a modification of the alignmentcontrol structures of FIG. 43;

FIGS. 148A and 148B are views showing a modification of the alignmentcontrol structures of FIG. 43;

FIGS. 149A and 149B are views showing a modification of the alignmentcontrol structures of FIG. 43;

FIGS. 150A and 150B are views showing a modification of the alignmentcontrol structures of FIG. 43;

FIGS. 151A and 151B are views showing a modification of the alignmentcontrol structures of FIG. 43;

FIGS. 152A to 152D are views showing a modification of the alignmentcontrol structures of FIG. 43;

FIGS. 153A to 153D are views showing a modification of the alignmentcontrol structures of FIG. 43;

FIGS. 154A to 154D are views showing a modification of the alignmentcontrol structures of FIG. 43;

FIGS. 155A and 155B are views showing a modification of the alignmentcontrol structures of FIG. 43;

FIGS. 156A and 156B are views showing a modification of the alignmentcontrol structures of FIG. 43; and

FIGS. 157A to 157D are views showing a modification of the alignmentcontrol structures of FIG. 43.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention will now be explained with reference to the preferredembodiments. FIG. 1 is a schematic cross-sectional view showing a liquidcrystal display apparatus according to the present invention. In FIG. 1,the liquid crystal display apparatus 10 includes a pair of transparentglass substrates 12 and 14, and a liquid crystal 16 having a negativeanisotropy of its dielectric constant inserted between the glasssubstrates 12 and 14. The first glass substrate 12 has an electrode 18and a vertical alignment layer 20, and the second glass substrate 14 hasan electrode 22 and a vertical alignment layer 24. Further, a polarizer26 is arranged on the outside of-the first glass substrate 2, and apolarizer 28 is arranged on the outside of the second glass substrate14. To simplify the explanation, the first glass substrate 12 will becalled the upper substrate, and the second glass substrate 14 will becalled the lower substrate.

In the case where the upper substrate 12 is configured as a color filtersubstrate, the upper substrate 12 further includes a color filter and ablack mask. In this case, the electrode 18 is a common electrode. In thecase where the lower substrate is configured as a TFT substrate, on theother hand, this lower substrate 12 includes an active matrix drivecircuit together with the TFTs. In this case, the electrode 22 comprisesa pixel electrodes.

FIG. 2 is a schematic cross-sectional view showing the liquid crystaldisplay apparatus of a vertical orientation type having alignmentcontrol structures for controlling alignment of the liquid crystal. Forsimplicity, the electrodes 18 and 22 and the alignment layers 20 and 24of FIG. 1 are not shown in FIG. 2. In FIG. 2, the upper substrate 12 hasprojections 30 protruded toward the lower substrate 14 as alignmentcontrol structures. In a similar fashion, the lower substrate 14 hasprojections 32 protruded toward the upper substrate 12 as alignmentcontrol structures. The projections 30 and 32 extend linearly in thedirection perpendicular to the page of FIG. 2.

FIG. 3 is a plan view of the projections 30 and 32 shown from thedirection of arrow III of FIG. 2. FIG. 3 further shows the portion ofone pixel of the active matrix drive circuit. The active matrix drivecircuit includes gate bus lines 36, drain bus lines 38, TFTs 40 andpixel electrodes 22. The projection 30 of the upper substrate 12 passesthrough the center of the pixel electrode 22, and the projections 32 ofthe lower substrate 12 pass through the gate bus lines 36. In this way,the projections 30 and 32 extend, in the top plan view, in parallel toeach other and are arranged alternately. The example of FIG. 3, however,is a very simple one, to which the arrangement of the projections 30 and32 is not limited.

As shown in FIG. 2, in the case where the liquid crystal 16 having anegative anisotropy of dielectric constant is arranged between thevertical alignment layers 20 and 24, the liquid crystal molecules 16Aare aligned in the direction perpendicular to the vertical alignmentlayers 20 and 24 when no voltage is applied thereto. In the neighborhoodof the projections 30 and 32, the liquid crystal molecules 16B arealigned in the direction perpendicular to the projections 30 and 32.

The projections 30 and 32 include slopes, and therefore the liquidcrystal molecules 16B aligned in the direction perpendicular to theprojections 30 and 32 are aligned at an angle to the vertical alignmentlayers 20 and 24.

Upon application of the voltage to the liquid crystal 16, the liquidcrystal 16 having a negative anisotropy of its dielectric constant isaligned perpendicular to the electric field, and therefore the liquidcrystal molecules lie substantially parallel to the substrate surfaces(vertical alignment layers 20 and 24). Normally, if the verticalalignment layers 20 and 24 are not rubbed, the direction in which theliquid crystal molecules lie is not decided, so the behavior of theliquid crystal is unstable. If the projections 30 and 32 extending inparallel to each other are provided as in this invention, however, theliquid crystal molecules 16B in the neighborhood of these projections 30and 32 are aligned at an angle to the vertical alignment layers 20 and24 as if pretilted, and therefore the direction in which the liquidcrystal molecules 16B lie is determined by the time of voltageapplication thereto.

Taking as an example the liquid crystal molecules between the projection30 on the left side on the upper substrate 14 and the projection 32 onthe lower left side below the projection 30 in FIG. 2, the liquidcrystal molecules 16B between these projections 30 and 32 are alignedfrom the upper right toward the lower left, and therefore, at the timeof voltage application thereto, the liquid crystal molecules 16B fall inthe direction parallel to the vertical alignment layers 20, 24 whilerotating in the clockwise direction. As a result, the liquid crystalmolecules 16A between these projections 30 and 32 fall in the directionparallel to the vertical alignment layers 20, 24 while rotating in theclockwise direction according to the behavior of the liquid crystalmolecules 16B. In a similar fashion, among the liquid crystal moleculesbetween the projection 30 on the left side of the upper substrate 14 andthe projection 32 on the lower right below the projection 30 in FIG. 2,the liquid crystal molecules 16B between the projections 30 and 32 arealigned from the upper left side down rightward, and therefore fall inthe direction parallel to the vertical alignment layers 20 and 24 whilerotating in the counterclockwise direction at the time of voltageapplication thereto. As a result, the liquid crystal molecules 16Abetween these projections 30 and 32 fall parallel to the verticalalignment layers 20 and 24 while rotating in the counterclockwisedirection according to the behavior of the liquid crystal molecules 16B.

FIGS. 4A and 4B are views showing the liquid crystal molecules 16Afalling at the time of voltage application thereto in accordance withthe arrangement of the projections 30 and 32 of FIGS. 2 and 3. FIG. 4Ais a plan view and FIG. 4B a cross-sectional view taken in line IVB-IVB.The liquid crystal molecules 16A on one side of the projection 30 of theupper substrate 12 fall toward the projection 30 while rotating in theclockwise direction (the direction along arrow X), while the liquidcrystal molecules 16A on the other side of the projection 30 of theupper substrate 12 fall toward the projection 30 while rotating in thecounterclockwise direction (the direction along arrow Y). By the way, inFIG. 4A, the liquid crystal molecules 16A are aligned perpendicular tothe page of FIG. 4A in the absence of a voltage applied thereto. In thisway, the liquid crystal alignment can be controlled without rubbing, anda plurality of areas having different directions of alignment of liquidcrystal molecules are created in one pixel. Therefore, the alignmentdivision is attained, thereby realizing a liquid crystal displayapparatus having a wide angular range with a superior visual field.

FIG. 5 is a plan view showing another example of the projections(alignment control structures) 30 and 32.

The projections 30 and 32 extend in parallel to each other while beingbent at the same time. In other words, the projections 30 and 32 arebent in zigzag fashion in parallel to each other. In this example, theliquid crystal molecules 16C and 16D on either side of the small,straight portion of the projections 30 and 32 are aligned in oppositedirections, and the liquid crystal molecules 16E and 16F on the eitherside of the next small, straight portion of the bend of the projections30 and 32 are aligned in opposite directions. The liquid crystalmolecules 16C and 16D are rotated by 90 degrees with respect to theliquid crystal molecules 16E, 16F.

As a result, the alignment division with four regions of differentliquid crystal alignments in one pixel can be attained for a furtherimproved visual field angle characteristic.

FIG. 6 is a view illustrating a liquid crystal display apparatus inwhich the alignment control structures are formed by the projections 30and 32. In FIG. 6, the electrode 18 arranged on the upper substrate 12and the electrode 22 arranged on the lower substrate 14 are shown. Theprojections 30 and 32 are formed as dielectric members on the electrodes18 and 22, respectively. Numeral 42 designates an electric field in theneighborhood of the projections 30 and 32. The projections 30 and 32 aremade of dielectric material, and therefore, the electric field 42 in theneighborhood of the projections 30 and 32 is an oblique one. Thus, atthe time of voltage application thereto, the liquid crystal moleculesfall perpendicular to the electric field 42 as indicated by arrows. Thedirection in which the liquid crystal molecules lie by the obliqueelectric field is the same as the direction in which the liquid crystalmolecules lie by the slopes of the projections 30 and 32.

FIG. 7 is a schematic cross-sectional view showing a liquid crystaldisplay apparatus in which the alignment control structures of the lowersubstrate 14 are the projections 32 and the alignment control structuresof the upper substrate 12 are slit structures 44. The slit structures 44includes the slits of the electrode 18 of the upper substrate 12.Actually, the vertical alignment layer 20 (not shown in FIG. 7) coversthe electrode 18 having the slits. Therefore, the vertical alignmentlayer 20 is recessed at the positions thereof corresponding to the slitsof the electrode 18. The slit structures 44 each include the slit in theelectrode 18 and the recessed portion of the vertical alignment layer20. These slit structures 44 extend linearly in a similar fashion to theprojections 30 of FIG. 6.

In the neighborhood of each slit structure 44, an oblique electric field42 is formed between the electrode 18 of the upper substrate 12 and theelectrode 22 of the lower substrate 14. This oblique electric field 42is similar to the oblique electric field 42 formed in the neighborhoodof the projections 30 in FIG. 6, and the liquid crystal molecules fallin accordance with the oblique electric field 42 at the time of voltageapplication thereto. In this case, the manner in which the liquidcrystal molecules fall is the same as the manner in which the liquidcrystal molecules fall in the presence of the projections 30. Thus, inthe same manner that alignment of the liquid crystal is controlled bythe combination of the projections 30 and 32 as shown in FIG. 6,alignment of the liquid crystal can be also controlled by thecombination of the slit structures 44 and the projections 32.

FIG. 8 is a schematic cross-sectional view showing a liquid crystaldisplay apparatus in which the alignment control structures of the uppersubstrate 12 and the lower substrate 14 are both slit structures 44 and46, respectively. Each slit structure 44 extends linearly in similarfashion to the projections 30 of FIG. 6, and the slit structures 46extend linearly in a similar manner to the projections 32 of FIG. 6. Inthe neighborhood of the slit structures 44 and 46, an oblique electricfield 42 is formed between the electrode 18 of the upper substrate 12and the electrode 22 of the lower substrate 14. This oblique electricfield 42 is similar to the oblique electric field 42 formed in theneighborhood of the projections 30 and 32 in FIG. 6, so that the liquidcrystal molecules fall in accordance with the oblique electric field 42at the time of voltage application thereto. In this case, the manner inwhich the liquid crystal molecules fall is the same as the manner inwhich the liquid crystal molecules fall in the presence of theprojections 30 and 32. Thus, in the same manner that alignment of theliquid crystal is controlled by the combination of the projections 30and 32 as shown in FIG. 6, alignment of the liquid crystal can becontrolled by the combination of the slit structures 44 and 46.

As a result, alignment of the liquid crystal can be controlled in thesame way by the projections 30 and 32 as by the slit structures 44 and46. Therefore, the projections 30 and 32 and the slit structures 44 and46 can be understood in common terms of alignment control structures (orlinearly arranged structures).

FIG. 9 is a cross-sectional view showing an example of the alignmentcontrol structures (linearly arranged structures) constituting theprojections 30 (32). The projections 30 are formed in the followingmanner, for example. The lower substrate 14 is formed with theelectrodes 22 together with the active matrix. Dielectric members 30A toconstitute projections are formed on the electrodes 22. The dielectricmembers 30A are formed by coating a resist and patterning it. Thevertical alignment layer 24 is formed on the dielectric member 30A andthe electrode 22. In this way, the projections 30 are formed.

FIG. 10 is a cross-sectional view showing an example of the alignmentcontrol structures (linearly arranged structures) in the form of theslit structures 44 (46). The slit structures 44 are formed in thefollowing manner, for example. After forming a color filter and a blackmatrix, etc., the electrode 18 is formed on the upper substrate 14. Theelectrode 18 is patterned thereby to form the slits 18A. A verticalalignment layer 20 is formed on the electrode 18 having the slits 18A.In this way, the slit structures 44 are formed.

FIG. 11 is a view explaining the problem of alignment of the liquidcrystal display apparatus having the linearly arranged structures.Although the linearly arranged structures are described hereinafterprimarily as the projections 30 and 32, the slit structures (sometimessimply called the slits) 44 and 46 may be used in place of theprojections 30 and 32 with equal effect.

FIG. 11 shows the state similar to that of FIG. 4. (FIG. 4, however,shows only the liquid crystal molecules 16A in the gap between theprojections 30 and 32, while FIG. 11 shows the liquid crystal moleculesexisting in the gap between the projections 30 and 32 and the liquidcrystal molecules existing on and in the neighborhood of the projections30 and 32. Also, in FIG. 11, the projection 32 of the lower substrate 14is located at the center.) Numeral 48 designates the arrangement of thepolarizers 26 and 28. The polarizers 26 and 28 are arranged at an angleof 45 degrees to the projections 30 and 32.

As described above, at the time of voltage application thereto, theliquid crystal molecules 16A existing in the gap between the projections30 and 32 come to lie perpendicular to the projections 32 on either sideof the projection 32 of the lower substrate (or the projection 30 of theupper substrate 12) in opposite directions. The liquid crystal moleculeson and in the neighborhood of the projections 30 and 32, which arelocated between the liquid crystal molecules 16A lying in oppositedirections, lie continuously with these liquid crystal molecules 16A.The liquid crystal molecules all come to be aligned in a plane parallelto the page of FIG. 11. In this case, the liquid crystal molecules justabove the projection 32 may fall rightward or fall leftward. It isuncertain whether the liquid crystal molecules located just above theprojections 32 fall rightward or leftward. For this reason, an alignmentcondition in which the liquid crystal molecules have fallen rightwardand another alignment condition in which the liquid crystal moleculeshave fallen leftward coexist on the same projection 32. At a place wherethese two alignment conditions are in contact with each other, aboundary of alignment of the liquid crystal (singular point in directorfield) is formed. A plurality of boundaries exist on the singleprojection 32.

Also, in the case where the liquid crystal on the projection 30 of theupper substrate 12 is aligned in the same manner as those on theprojection 32 of the lower substrate 14 (in the area C, for example),the alignment between the projections 30 and 32 assumes a bent form.

In the case where the liquid crystal is differently oriented on theprojection 30 of the upper substrate 12 from those on the projection 32of the lower substrate 32 (in the area A, for example), on the otherhand, the alignment between the projections 30 and 32 assumes a sprayform. Specifically, two types of alignment conditions coexist betweenthe projections 30 and 32, and a boundary is formed between these areasof different alignment.

In more detail, even an alignment in the spray form, for example, isslightly different when the upper and lower substrates 12 and 14 aremisaligned. The result is different angles of the polarizers 26 and 28at which the transmittance is maximum in the respective areas. Thiscondition was actually measured by rotating the polarizers 26 and 28 inseveral areas. In FIG. 11, area A shows that the polarizers 26 and 28have been rotated by about −13 degrees with respect to a normalarrangement 48. The area B shows that the polarizers 26 and 28 have beenrotated by −4 degrees with respect to the normal arrangement 48. Thearea C, on the other hand, shows that the polarizers 26 and 28 have beenrotated by +2 degrees with respect to the normal arrangement 48.

FIG. 12 is a view showing transmittance measured in the areas A, B and Cof FIG. 11. The curve A represents the measurement in the area A of FIG.11, the curve B the measurement in the area B of FIG. 11, and the curveC the measurement in the area C of FIG. 11. The curve A indicates that aconsiderably high transmittance is obtained at an angle of thepolarizers 26 and 28 considerably displaced from the normal arrangement(45 degrees with respect to the projections 30 and 32), while in thecase where the polarizers 26 and 28 are in the normal arrangement 48 (45degrees with respect to the projections 30 and 32), light cannot besubstantially transmitted. The curve B indicates that a comparativelyhigh transmittance is obtained in the case where the polarizers 26 and28 are located at an angle somewhat displaced from the normalarrangement 48 (45 degrees with respect to the projections 30, 32). Thecurve C shows that some degree of transmittance can be secured in thecase where the polarizers 26 and 28 are in the normal arrangement 48 (45degrees with respect to the projections 30, 32). In this way, the use ofthe projections 30 and 32 produces a plurality of areas of differenttransmittance characteristics.

FIG. 13 is a view showing the change in transmittance after voltageapplication. In FIG. 13, voltage is applied at 1000 ms, and voltage isremoved at 2000 ms. In the case where areas of different alignmentsexist as described with reference to FIGS. 11 and 12, a phenomenoncalled overshoot occurs immediately after voltage application.Specifically, the transmittance increases greatly, for example, rightafter voltage application, and then, gradually decreases to apredetermined value where it comes into equilibrium. The overshoot isexpressed by the degree the white brightness has increased from thetransmittance in equilibrium. The overshoot (%) is defined as(Y−X)/X×100, where the initial brightness is X and the brightness inequilibrium is Y.

As shown in FIG. 11, if the areas A, B and C having differenttransmittances exist, the liquid crystal in the areas A, B and Ccontinues to move in the respective areas after voltage application, andthe liquid crystal in adjacent areas affects each other, so that theareas A, B and C themselves continue to move (i.e. the boundariesbetween areas A, B and C continue to move).

As a result, the transmittance increases and so does the overshoot. Theovershoot is a cause of the afterimage, often leading to thedeterioration of the display quality. Also, in the presence of areas A,B and C having different features, the display performance may develop adifference, thereby making it impossible to obtain a predeterminedquality.

For this reason, it is desired to control alignment of the liquidcrystal on the projections 30 and 32 to prevent the liquid crystal inareas having different transmittances from continuing to movepersistently and thereby to improve brightness and response.

FIG. 14 is a view showing an example of the projections (linearlyarranged structures) 30 and 32 according to the first embodiment of thepresent invention. Slit structures 44 and 46 can of course be used inplace of the projections 30 and 32 as the linearly arranged structures.

The liquid crystal display apparatus has the projections 30 of the uppersubstrate 12 and the projections 32 of the lower substrate 14, asdescribed above. Each projection 30 or 32 is formed of a plurality ofconstituent units 30S or 32S. The constituent units 30S or 32S have asubstantially uniform shape, and are distinguished from each other by achange in the shape or cutting. In the example of FIG. 14, two adjacentconstituent units 30S or 32S are connected by a narrow portion. Also,the constituent units 30S of the projections 30 of the upper substrate12 and the constituent units 32S of the projection 32 of the lowersubstrate 14 extend in parallel to each other, and the constituent unitsof the projections 30 of the upper substrate 12 and the correspondingconstituent units of the projections 32S of the lower substrate 14 arearranged at such positions as to be overlapped with each other.

As described above, each projection 30 or 32 is formed of a plurality ofthe constituent units 30S or 32S, respectively and, therefore, there isless likelihood of forming a plurality of areas A, B and C havingdifferent transmittances as shown in FIG. 11 within each constituentunit 30S or 32S. Also, the areas A, B and C are prevented fromcontinuously moving (the boundaries between the areas A, B and C areprevented from continuing to move), so that the liquid crystal comes tobe stably aligned in the horizontal state within a shorter time. As aresult, overshoot is reduced, thereby improving both the brightness andthe response speed. Even if there are areas with a large transmittanceloss, the effect thereof can be offset by the presence of a multiplicityof small areas with a small transmittance loss. For this purpose, eachprojection 30 or 32 desirably includes as many constituent units 30S or32S as possible, respectively. Preferably, the length of the constituentunits 30S or 32S is not less than the length of the gap between theprojections 30 and 32 of the pair of substrates 12 and 14, and not morethan 200 μm.

FIG. 15 is a view showing a modification of the projections 30 and 32.The projections 30 and 32 are each configured of a plurality ofconstituent units 30S and 32S. In this example, the projections 30 and32 are cut off, i.e. the constituent units 30S and 32S are separatedfrom each other. The other features are similar to those of the exampleof FIG. 14.

FIG. 16 is a view showing a modification of the projections 30 and 32.The projections 30 and 32 are each formed of a plurality of constituentunits 30S and 32S. In this example, the projections 30 and 32 are bent.The other features are similar to that of FIG. 15.

FIG. 17 is a view showing a modification of the projections 30 and 32.The projections 30 and 32 are each configured of a plurality ofconstituent units 30S and 32S. In this case, the projections 30 and 32are cut off, i.e. the constituent units 30S and 32S are separated fromeach other. Further, the constituent units 30S of the projections 30 ofthe upper substrate 12 and the constituent units 32S of the projections32 of the lower substrate 14 extend in parallel to each other and areshifted from each other. The constituent units 30S and 32S making up theprojections 30 and 32 of the upper and lower substrates, respectively,which are in contact with each other as shown in FIG. 14, may of coursebe shifted as shown in FIG. 17.

FIG. 18 is a view showing a modification of the projections 30 and 32.The projections 30 and 32 are each configured of a plurality ofconstituent units 30S and 32S. In this case, the projections 30 and 32are cut off, i.e. the constituent units 30S and 32S are separated fromeach other. Further, the constituent units 30S of the projections 30 ofthe upper substrate 12 and the constituent units 32S of the projections32 of the lower substrate 14 have different lengths. The constituentunit 30S of the projections 30 of the upper substrate 12 is about threetimes as long as the constituent unit 32S of the projections 32 of thelower substrate 14. The center of the constituent unit 30S of theprojections 30 of the upper substrate 12 coincides with the center ofthe three constituent units 32S of the projections 32S of the lowersubstrate 14.

FIG. 19 is a view showing a modification of the projections 30 and 32.The projections 30 and 32 are each formed of a plurality constituentunits 30S and 32S. In this example, the projections 30 and 32 are cutoff, i.e. the constituent units 30S and 32S are separated from eachother. Further, the constituent units 30S of the projections 30 of theupper substrate 12 have different lengths, and so are the constituentunits 32S of the projections 32 of the lower substrate 14. In thisexample, the constituent units 30S and 32S each have two types oflength, and those constituent units having different lengths are formedinto a set, so that sets of different lengths are arranged alternately.The set of the constituent units 30S of the projections 30 of the uppersubstrate 12 and the set of the constituent units 32S of the projections32 of the lower substrate 14 are arranged in a staggered fashion. Theconstituent units 30S, 32S of FIGS. 18 and 19 can be arranged at acoincident position or connected as in the preceding embodiments.

FIG. 20 is a view showing a modification of the projections 30 and 32.Each of the projections 30 and 32 is formed of a plurality ofconstituent units 30S, 32S, respectively. In this example, theconstituent units 30S of the projection 30 are arranged alternately withthe constituent units 32S of the projection 32, and the constituentunits 32S of the projection 32 are arranged alternately with theconstituent units 30S. For example, the constituent units 30S of theprojection 30 of the upper substrate are arranged at every otherposition of the projection 30 of FIG. 2, and the constituent units 32Sof the projection 32 of the lower substrate are arranged at every otherposition free of the constituent units 30S of the projection 30 of theupper substrate just under the projection 30 of FIG. 2. Apparently, theprojections 30 and 32 of the upper and lower substrates appear to formeach train of a mixture of constituent units 30S, 32S of the projections30 and 32 of the upper and lower substrates, respectively.

In the examples described above, the constituent units 30S and 32S areshown in elliptical form. The present invention, however, is not limitedto the elliptical shape but may be rectangular, rhombic or otherwisepolygonal. Also, for the purpose of averaging the length of theconstituent units 30S and 32S of the projections 30 and 32, the lengthis preferably equal to that of the combination of the pixels of R, G andB, i.e. not more than 200 μm. Also, since the projection gap with thepair of the substrates overlapped with each other constitutes theminimum distance for controlling the alignment of the liquid crystal,the length of the constituent units 30S and 32S of the projections 30and 32 is also preferably not less than the projection gap.

Although the case involving the projections 30 and 32 is describedabove, this is also the case with the slit structures 44 and 46including the slits in the electrode. In other words, the slit is formedof a plurality of constituent units. In this case too, the arrangementsdescribed above can be used as they are. This also applies to thelimitation of the length of the constituent units.

FIG. 21 is a view showing a modification of the linearly arrangedstructures. FIG. 21 shows portions of the three pixel electrodes 22R,22G and 22B, and the linearly arranged structures are in the zig-zagbent form, as shown in FIG. 5. The linearly arranged structures of theupper substrate 12 includes projections 30, and the linearly arrangedstructures of the lower substrate 14 includes slit structures 46. Inother words, the combination of the linearly arranged structures of FIG.21 is equivalent to the combination of the projections and the slitstructures of FIG. 7, arranged upside down.

FIG. 22 is a view showing the pixel electrode 22R and the slitstructures 46 of FIG. 21. The pixel electrode 22R has a plurality ofslits 22S and a plurality of inter-slit portions 22T of the samematerial (ITO) as the pixel electrode 22R. The slits 22S can be formedat the time of patterning the pixel electrode 22R. The verticalalignment layer 24 is coated on the pixel electrode 22R, so that theseries of slits 22S of the pixel electrode 22R constitutes the slitstructure 46, and the slits 22S make up the constituent units 46S of theslit structure 46. The material portions 22T are portions where adjacentconstituent units 46S are separated.

In this embodiment, the width of the slits 22S (the constituent unit 46Sof the slit structure 46) is 5 μm, and the length thereof is 12 μm, 26μm or 33 μm. The length of the slit 22S (the constituent unit 46S of theslit structure 46) is preferably not less than 10 μm. The length of thematerial portion 22T is 4 μm. The length of the material portion 22T ispreferably not more than the width of the projection 30. In a similarfashion, the width of the constituent unit 30S of the projection 30 is 5μm, and the length thereof is 12 μm, 26 μm or 33 μm. The length of thegap between the constituent units 30S of the projection 30 is 4 μm.

FIGS. 23A to 23E are views explaining the formation of the linearlyarranged structures configured of the projections 30. As shown in FIG.23A, a substrate 12 is prepared and a color filter, a black matrix andan electrode 18 are applied onto it. As shown in FIG. 23B, LC200 (madeby Shipley) constituting a positive resist 50 is spin coated on thesubstrate 12 having the electrode 18 (not shown) for 30 seconds at 1500rpm. The positive resist is used here but it is not necessarily used. Anegative resist or a photosensitive resin other than the resist is apossible alternative. As shown in FIG. 23C, the spin-coated resist 50 isprebaked at 90° C. for 20 minutes, and then subjected to contactexposure through a photo mask 52 (exposure time 5 seconds). As shown inFIG. 23D, after development with the developer (by Shipley) for oneminute, the resist is post-baked at 120° C. for 60 minutes followed byanother post baking at 200° C. for 40 minutes thereby to form aprojection 30. The width of this projection 30 is 5 μm, the heightthereof is 1.5 μm, and the length of the constituent units 30S of theprojections 30 is described above. As shown in FIG. 23E, a verticalalignment layer JALS684 (made by JSR) is spin coated at 2000 rpm for 30seconds, followed by baking at 180° C. for 60 minutes thereby to formthe vertical alignment layer 20.

A seal (XN-21F, made by Mitsui Toatsu Chemical) is applied to thissubstrate 12 or the TFT substrate 14, and the remaining substrate issprayed with spacers (SP-20045, made by Sekisui Fine Chemical) of 4.5μm. The two substrates are laid one on the other. In the last step, anempty panel is produced by baking at 135° C. for 60 minutes. Rubbing andcleaning was not conducted. In vacuum environment, the empty panel isfilled with the liquid crystal MJ961213 (made by Merck) having anegative anisotropy of its dielectric constant by vacuum-filling method.The insertion port is finally sealed with a sealing material (30Y-228,made by Three Bond) thereby to produce a liquid crystal panel.

The transmittance of the liquid crystal panel produced in this way wasmeasured with the voltage of 5 V applied thereto. The measurement was25.7%. Also, the measurement of the response speed upon application ofvoltages of 0 V to 5 V shows an overshoot of 1.6%.

In the case of the liquid crystal display apparatus having the linearlyarranged structures of FIG. 15, the measurement of the transmittanceupon application of 5 V thereto is 26.3%. The response speed as measuredupon application of voltages of 0 V to 5 V indicates the overshoot of1.1%. The width of the projections is 10 μm, the height thereof is 1.5μm, the length of the constituent unit of the projections is 30 μm, thedistance between the projection constituent units is 10 μm, and the gapbetween the projections with the upper and lower substrates laid one onthe other is 20 μm.

In the case of the liquid crystal display apparatus having the linearlyarranged structures shown in FIG. 17, on the other hand, the measurementof the transmittance upon application of 5 V thereto is 26.6%. Theresponse speed as measured upon application of voltages of 0 V to 5 Vindicates the overshoot of 0.9%. In the case of the liquid crystaldisplay apparatus having the linearly arranged structures of FIG. 18,the measurement of the transmittance upon application of 5 V is 26.1%.Also, as a measurement of the response speed taken by applying voltagesof 0 V to 5 V, the overshoot is 1.6%. In this case, the width of theprojection is 10 μm, the height thereof is 1.5 μm, the length of theprojection constituent unit is 30 μm, the length of the other projectionconstituent unit is 70 μm, the gap between the projection constituentunits is 10 μm and the projection gap with the upper and lowersubstrates laid one on the other is 20 μm. Also, a panel is produced byattaching a pair of the upper and lower substrates to each other in sucha manner that each long projection constituent unit is located at thesame position as two short projection constituent units.

In the case of the liquid crystal display apparatus having the linearlyarranged structures shown in FIG. 20, on the other hand, the measurementof the transmittance upon application of 5 V is 26.0%. Also, theresponse speed as measured upon application of 0 V to 5 V is 1.6% interms of the overshoot. In this case, the projection has a width of 10μm and a height of 1.5 μm, the length of the projection constituent unitis 30 μm, a gap between the projection constituent units is 50 μm,another gap between the projection constituent units is 10 μm, and theprojection gap with the upper and lower substrates laid one on the otheris 20 μm. Also, the projections are formed in such a manner that theprojection constituent units of one substrate are located at positionscorresponding to the gaps between the projection constituent units ofthe other substrate.

The following measurement is conducted as a comparative example 1.Projections having no constituent units are formed to produce a liquidcrystal panel. The width of the projections is 10 μm, the height thereofis 1.5 μm, and the projection gap with the upper and lower substrateslaid one on the other is 20 μm. The measurement of the transmittanceupon application of 5 V is 22.8%. Also, the measurement of the responsespeed upon application of voltages of 0 V to 5 V indicates an overshootof 7.5%.

The following measurement is taken as a comparative example 2. A liquidcrystal panel having projections similar to those of FIG. 15 with longerprojection constituent units is prepared. The width of the projectionsis 10 μm, the height thereof is 1.5 μm, the length of the projectionconstituent units is 300 μm, the gap between the projection constituentunits is 10 μm, and the projection gap with the upper and lowersubstrates laid one on the other is 20 μm. The measurement of thetransmittance taken upon application of 5 V is 23.5%. Also, themeasurement of the response speed upon application of 0 V to 5 Vindicates the overshoot of 6.3%.

The following measurement is taken as a comparative example 3. A liquidcrystal panel having projections similar to FIG. 15 with shorterconstituent units is prepared. The width of the projections is 10 μm,the height thereof is 1.5 μm, the length of the projection constituentunits is 10 μm, the gap between the projection constituent units is 10μm, and the projection gap with the upper and lower substrates overlaidone on the other is 20 μm. The measurement taken of the transmittanceupon application of 5 V is 24.1%. Also, the response speed as measuredupon application of 0 V to 5 V indicates the overshoot of 5.9%.

FIG. 24 is a view showing the alignment of the liquid crystal of aliquid crystal display apparatus having linearly arranged structuressimilar to those of FIG. 11. FIG. 25 is a view showing the displaycharacteristic of the configuration shown in FIG. 24. In FIG. 25,numeral 54 designates an area which appears dark.

In FIG. 24, the liquid crystal molecules located between the projection30 of the upper substrate 12 and the projection 32 of the lowersubstrate 14 are aligned substantially perpendicular to the projections30 and 32. Also, the liquid crystal molecules located on the projections30 and 32 are aligned substantially parallel to the projections 30 and32.

It has been found that the boundaries (singular points in directorfield) and the number of divisions of the areas having differentalignment conditions on the projections 30 and 32 continue to change forseveral seconds or several tens of seconds in some cases after voltageapplication. It has also been found that the recognition of thisphenomenon as a change in transmittance of the liquid crystal panel is aprincipal cause of overshoot.

This phenomenon is considered to be caused by the following fact. Theliquid crystal molecules on the projections 30 and 32 are considered tobe aligned either rightward or leftward in the case where theprojections 30 and 32 extend horizontally, as shown in FIG. 24, forexample. In the absence of means for controlling the direction, however,the liquid crystal molecules fall randomly in one of two directionsimmediately after voltage application. After that, the areas ofdifferent alignment conditions on the projections 30 and 32 affect eachother. Due to the absence of regulation of the directions of thealignment in these areas, however, the liquid crystal molecules easilychange the status thereof under the effect from the surrounding. In thisway, the liquid crystal in the areas of different orientations on theprojections 30 and 32 is considered to continue to change for a longtime.

As described above, the projections or slit-structures configured of aplurality of constituent units has made it possible to regulated thedirections of alignments by division points of constituent units.

FIG. 26 is a view showing an alignment of the liquid crystal of theliquid crystal display apparatus having linearly arranged structuresincluding a plurality of constituent units. FIG. 27 is a view showingthe display characteristic of the configuration of FIG. 26. In FIG. 27,numeral 54 designates an area which appears dark. FIGS. 26 and 27indicate the features of the liquid crystal molecules of the liquidcrystal display apparatus of FIG. 15, for example.

The projections 30 and 32 are divided into areas having differentalignments on the projections 30 and 32 at the cut portions 30T and 32T.The observation shows that the liquid crystal undergoes no secularvariation at the cut portions 30T and 32T. It has been newly found,however, that a plurality of areas having different orientations of theliquid crystal exist also between the cut portions 30T and 32T andadjacent cut portions (in the constituent units 30S and 32S of theprojections). The boundaries (singular points) between these areas havebeen found to undergo an age-based variation which, though minor,indicates room of further improvement of the overshoot.

FIG. 28 is a view showing the alignment of the liquid crystal of theliquid crystal display apparatus having the linearly arranged structuresaccording to the second embodiment of the present invention. FIG. 29 isa view showing the display characteristic of the configuration shown inFIG. 28. FIG. 30 is a view showing, in enlarged form, the features ofthe boundaries (singular points) of alignment of first type and thefeatures of the boundaries (singular points) of alignment of second typeindicated in FIG. 28.

In FIGS. 28 and 30, a study of the means capable of controlling thealignment of the liquid crystal on the projections 30 and 32 shows thatthere are two types of boundaries (singular points in director field),regarding boundaries of a plurality of areas having different liquidcrystal alignment conditions. In the first type (I), the liquid crystalmolecules around a point are directed toward said point. In the secondtype (II), some of the liquid crystal molecules around a point aredirected to said point while the remaining ones are directed opposite tothe same one point. In FIG. 28, the liquid crystal molecules are eachshown to have a head and a leg. In the first type (I), all the heads orall the legs of all the liquid crystal molecules are directed to thecenter. In the second type (II), on the other hand, some liquid crystalmolecules have the heads thereof directed to the center while theremaining liquid crystal molecules have the legs thereof directed to thecenter.

In FIG. 28, the projections 30 and 32 constituting the linearly arrangedstructures of each substrate include means 56 for forming boundaries ofalignment of first type (I) in which the liquid crystal moleculessurrounding a point are directed toward said point, and means 58 forforming the boundaries of alignment of second type (II) in which a partof the liquid crystal molecules surrounding a point are directed towardsaid point and the remaining liquid crystal molecules are directed awayfrom the same one point. The means 56 for forming the boundaries ofalignment of first type (I) are arranged in the constituent units 30Sand 32S of the projections 30 and 32, while the means 58 for forming theboundaries of alignment of second type are arranged in the boundariesbetween the constituent units 30S and 32S of the projections 30 and 32(i.e. in the separation sections 30T and 32T for separating theconstituent units 30S and 32S).

As seen from the foregoing description and FIG. 2, the projections 30and 32 can control the alignment of the liquid crystal molecules bymeans of the main slopes thereof In a similar fashion, the separationsections 30T and 32T defining the boundaries (singular points indirector field) between the constituent units 30S and 32S of theprojections 30 and 32 also have slopes with which the alignment of theliquid crystal molecules can be controlled. The slopes of the separationsections 30T and 32T generally extend transversely to the length ofprojections 30 and 32. The main slopes of the projections 30 and 32 havethe function to align the liquid crystal molecules perpendicular to thelength of the projections 30 and 32. The slopes of the separationsections 30T and 32T, in contrast, are adapted to align the liquidcrystal molecules substantially parallel to the length of theprojections 30 and 32. On the other hand, the liquid crystal moleculesare generally aligned perpendicular to the length of the projections 30and 32, and the function is similar for the separation sections 30T and32T. Thus, the separation sections 30T and 32T constitute means 58 forforming the boundary of second type (II).

FIGS. 31 and 32 show specific examples of the means 56 for forming theboundaries of alignment of first type (I). FIG. 32 is a cross-sectionalview of both the cross-section passing through the projection 30 of theupper substrate 12 and of the cross-section passing through theprojection 32 of the lower substrate 14. The means 56 includes dot-likeprojections formed on the projections 30 and 32, respectively. The means56 aids the alignment of the liquid crystal in terms of shape orelectric field and thus can align the liquid crystal molecules in themanner described above. With this portion as a nucleus, the alignmentareas of the liquid crystal on the projections 30 and 32 can be divided.The liquid crystal is differently aligned in the boundary of first type(I) and the boundary of second type (II), and therefore the projectionshave naturally different effects on them.

The means 56 for forming the boundaries of alignment of a first type (I)can cause the liquid crystal molecules to lie toward the higher positionon the projections on the upper substrate 12. Only after the cutportions and the heights of the projection are arranged alternately inthis way, can the directions of alignments of all the domains on theprojection be determined. Thus, the age-based variation of the domainsof the liquid crystal after voltage application can be suppressed, andthe overshoot can be eliminated substantially in its entirety.

In order to form the means 56 projecting on the projections 30 and 32,small structures are formed before forming the projections 30 and 32.The small structures may alternatively be formed after forming theprojections 30 and 32. The small structure has a size of 10 μm squareand a height of 1 μm. The small structures are made of the same materialas the projections in the case under consideration. For forming thesmall structures on the TFT substrate, a method is available in which awiring metal layer or an dielectric layer is deposited at the particularportion. For the CF substrate, on the other hand, the desired structurecan be obtained without increasing the number of processes by depositinga color layer or a BM at the particular portion.

A photosensitive acrylic material PC-335 (made by JSR) is used for theprojections. The projections have the width of 10 μm, the projection gap(the distance from the projection end of one substrate to the projectionend of the other substrate after the substrates are attached to eachother) is 30 μm, and the projection height is 1.5 μm (the height of theprojection which is originally 1 μm higher is 2.5 μm tall). Theseparated sections 30S and 32S of the projections 30 and 32 have thesize of 10 μm square, and the distance from the center of the separatedsections 30S and 32S to the center of the height 56 of the projections30 and 32 is 60 μm (the projection 1.5 μm all exists continuously forthe length of 50 μm).

The vertical alignment layer is made of JALS-204 (made by JSR). Microbar(made by Sekisui Fine Chemical) 3.5 μm in diameter is used as a spacermixed with the liquid crystal, and MJ95785 (made by Merk) as a liquidcrystal material.

FIGS. 33 and 34 are a plan view and a cross-sectional view,respectively, showing a modification of the linearly arrangedstructures. This example is similar to the preceding one except for thefollowing points. Specifically, the upper and lower substrates 12 and 14have projections 30 and 32, respectively, and the tall portions and thelow portions are alternately formed in the projections 30 and 32 as themeans 56 for forming the boundaries of alignment of first type (I) andthe means 58 for forming the boundaries of alignment of second type(II). The low portions 58 of the projections 30 and 32 are theseparation sections 30T and 32T for separating the constituent units 30Sand 32S. The low portions have the projection height of 1 μm. As amethod of reducing the height of the projection, according to thisembodiment, the projections 30 and 32 formed in this embodiment areselectively ashed by radiation from an oxygen plasma. Also, in the casewhere the projections are formed on the TFT substrate, the desiredstructure can be obtained by a method for opening contact holes in theparticular portion. For a CF substrate, on the other hand, a method forremoving the color layer and the overcoat layer of the particularportion can be used without increasing the processes.

FIG. 35A is a plan view showing a modification of the linearly arrangedstructures. The upper and lower substrates 12 and 14 have projections 30and 32. The projections 30 and 32 have alternately wide portions andnarrow portions as the means 56 for forming the boundaries of alignmentof first type (I) and the means 58 for forming the boundaries ofalignment of second type (II). The width of the wide portion 56 is 15μm, and the width of the narrow portion 58 is 5 μm (normally, the widthis 10 μm).

FIG. 35B is a plan view showing a modification of the linearly arrangedstructures. The upper and lower substrates 12 and 14 have projections 30and 32. A wide portion and a narrow portion of the projections 30 and 32are alternately arranged as the means 56 for forming the boundaries ofalignment of first type (I), and the means 58 for forming the boundariesof alignment of second type (II).

FIG. 36 is a plan view showing a modification of the linearly arrangedstructures. The lower substrate 14 has slits 46 as the linearly arrangedstructures. The width of the slit 46s is continuously changed and wideportions are alternated with narrow portions, as the means 56 forforming the boundaries of alignment of first type (I) and the means 58for forming the boundaries of alignment of second type (II).

FIG. 37 is a plan view showing a modification of the linearly arrangedstructures. The upper substrate 12 is a CF substrate, and the lowersubstrate 14 is a TFT substrate. The panel size is 15 inch type, and thenumber of pixels is 1024×768 (XGA). FIG. 37 shows one pixel unit of thepanel. The height of the central portions 32P of the projections 32 ofthe TFT substrate 14 is reduced, and the height of the central portions30P of the projections 30 of the CF substrate 12 is increased. Takingthe effect of the edge of the pixel electrodes 22 into account, thedesired alignment could be realized.

In an application of the present invention to a liquid crystal panelusing a TFT substrate, it is necessary to take into full considerationthe effect of the edge of the pixel electrodes 22 of the TFT substrateon the direction of the electric field.

FIGS. 38A and 38B are partial cross-sectional views showing theneighborhood of the edge of the pixel electrode 22 of the liquid crystaldisplay apparatus, and FIGS. 39A and 39B are views showing the alignmentof the liquid crystal at the edge of the pixel electrode 22 of FIGS. 38Aand 38B. FIGS. 38A and 39A show a portion of the projection 30 of theupper substrate 12, and FIGS. 38B and 39B a portion of the projection 32of the lower substrate 14. As shown in FIGS. 38A to 39B, an obliqueelectric field 60 exists at the edge of the pixel electrode 22. Thisoblique electric field 60 plays the role of directing the liquid crystalmolecules toward the center of the pixel, when viewed, so that the TFTsubstrate is arranged below the CF substrate. This indicates that theedge of the pixel electrode 22 has the same function as the means 56 forforming the boundary of orientation of first type (I) on the projection32 of the TFT substrate, and has the same function as the means 58 forforming the boundaries of second type (II) against the projection 30 ofthe CF substrate.

In other words, the boundary nearest to the edge of the pixel electrodeon the projection 32 of the TFT substrate always assumes the status ofalignment of second type (II) and the boundary nearest to the edge ofthe pixel electrode always assumes the status of first type (I) on theprojection 30 of the CF substrate. As a result, the configuration ofFIG. 37 permits the alignment control of all the domains on theprojection for the TFT liquid crystal panel by determining the directionof alignment on the projections 30 and 32 in accordance with thedirection of regulation by the edge of the pixel electrode.

FIG. 40 is a plan view showing a modification of the linearly arrangedstructures. For the TFT substrate, the projection height is reduced asthe alignment control means 58 on the projection 32 nearest to the edgeof the pixel electrode, while the projection height is increased as thealignment forming means 56 inside. For the CF substrate, on the otherhand, the projection height is increased as the alignment control means56 on the portion of the projection 30 nearest to the pixel edge, whilethe projection height is reduced as the alignment forming means 58inside.

In the embodiments described above, the dot-projections are formed inthe same manner for the upper and lower substrates, but it is notnecessary to do so. For example, the upper substrate may be formed withhigher dot-projections and lower dot-projections, while the lowersubstrate may be formed with wider dot-projection and narrowerdot-projections with equal effect. Also, only the two types of shapesneed not be alternated on the same projections.

For example, the repetition of higher and lower dot-projections is notalways necessary, but an alternative is to arrange a higherdot-projection, a lower dot-projection, a wider dot-projection, anarrower dot-projection, a higher dot-projection and a lowerdot-projection in that order, for example. Anyway, the only requirementis to alternate the shape change satisfying the conditions for theboundaries of first and second types (I) and (II). This shape change forthe projections and the slits is shown in Table 1.

TABLE 1 Boundary forming means 56 of first type (I) Increase projectionheight Increase projection width Remove electrode under projectionIncrease slit height (protrude) Increase slit width Boundary formingmeans 58 of second type (II) Cut projection Reduce projection heightReduce projection width Cut slit Reduce slit height (form a hole) Reduceslit width

FIG. 41 is a view showing the alignment of the liquid crystal on thelinearly arranged structures of FIG. 35. In this case, the alignment inthe display domain is the bend form.

FIG. 42 is a view showing a modification of the linearly arrangedstructure of FIG. 41. In this case, the alignment of the display domainis the spray form. By changing from the configuration of FIG. 41 to theconfiguration of FIG. 42, the bend alignment can be changed to the sprayalignment.

FIG. 43 is a plan view showing the alignment control structuresaccording to the third embodiment of the present invention. FIG. 44 is across-sectional view passing through the alignment control structures ofFIG. 43. The basic configuration of this liquid crystal displayapparatus is similar to that of the liquid crystal display apparatusaccording to the embodiment shown in FIGS. 1 to 5. Specifically, theliquid crystal display apparatus 10 includes projections 30 and 32 asthe alignment control structures (linearly arranged alignment controlstructures) for controlling the alignment of the liquid crystal betweenthe projections 30 and 32 (display domain). The projections 30 and 32are arranged in the direction parallel to each other and displaced fromeach other, as viewed normal to the substrate. FIG. 44 is across-sectional view passing through the projection 32 of the lowersubstrate 14 and the projection 30 of the upper substrate 12 is notshown in FIG. 44.

In this embodiment, the upper substrate 12 and the lower substrate 14include means 62 and 64, respectively, for forming the boundary ofalignment of the liquid crystal molecules (singular points in directorfield) at fixed positions on the opposed substrate upon application of avoltage thereto. In FIG. 44, the upper substrate 12 includes means 62having a dot-projection 62 a in the same cross-section as the projection32 of the lower substrate 14. In a similar fashion, as shown in FIG. 43,the lower substrate 14 includes means 64 having a dot-projection 64 a inthe same cross-section as the projection 30 of the upper substrate 12.

FIG. 45 is a view showing the alignment of the liquid crystal in theneighborhood of the linearly arranged structure of FIG. 44. FIG. 46 is aview showing the alignment of the liquid crystal in the neighborhood ofthe linearly arranged structure according to the first embodiment.

In the first embodiment, the projections 30 and 32 are each formed of aplurality of constituent units 30S and 32S. The means 62 and 64 forforming the boundary of alignment of the liquid crystal molecules at apredetermined position according to this embodiment have the samefunction as the projections 30 and 32 formed of a plurality ofconstituent units 30S and 32S in the first embodiment. As seen from thecomparison between FIGS. 45 and 46, the positions where the means 62 and64 are formed along the projections 30 and 32 of the means 62 and 64 arethe same as the cut portions or the boundaries of a plurality ofconstituent units 30S and 32S in the first embodiment.

As shown in FIGS. 44 and 45, the means 62 is intended to cause theliquid crystal molecules on the projection 32 to fall toward thedot-projection 62 a of the means 62. In similar fashion, the means 64 isadapted to cause the liquid crystal molecules on the projection 30 tolie toward the projection 64 a of the means 64. Thus it is seen that themeans 62 and 64 have the same significance as the projections 30 and 32formed of a plurality of constituent units 30S and 32S whereby theliquid crystal molecules tend to lie toward the cut portions or theboundaries 32T.

In the configuration of FIG. 46, the liquid crystal molecules located onthe side of the projection 32 are desirably aligned perpendicular to theprojection 32. The liquid crystal molecules on the side of the cutportions or the boundaries 32T where the projection 32 is discontinuous,however, are not necessarily turned perpendicular to the projection 32.In the configuration of FIGS. 44 and 45, the projection 32 is notdiscontinuous, and therefore the liquid crystal molecules located on theside of the projection 32 are all positioned perpendicular to theprojection 32. Thus, the alignment of the liquid crystal in both thedisplay area and the area on the projection can be controlled withoutreducing the brightness.

The dot-projections 62 a and 64 a are made of the photosensitive acrylicmaterial PC-335 (made by JSR). The dot-projections 62 a and 64 a havethe width of 5 μm and the height of 1.5 μm. The width of the linearprojections 30 and 32 is 10 μm and the height thereof is 1.5 μm.

FIGS. 47A to 47C are views showing a modification of the linearlyarranged structure and the control means for the boundary alignment.FIG. 47A is a cross-sectional view, FIG. 47B an illustrative perspectiveview, and FIG. 47C is a plan view. In this embodiment, the means 62 forforming the boundary of alignment of the liquid crystal molecules at apredetermined position is a dot-slit structure 62 b on the opposedsubstrate. The means 62 is arranged by forming a slit in the electrode18 and forming the vertical alignment layer 20 on the electrode 18. Thesize of the slit is 14×4 μm or 10×4 μm at which the display brightnessis improved. The slit width can be further reduced.

FIG. 48 is a view showing a modification of the control means foralignment in the boundaries and the linearly arranged structures. Inthis embodiment, the means 62 for forming the boundary of alignment ofthe liquid crystal molecules at a predetermined position is thedot-projection 62 a. The dot-projection 62 a is produced in such amanner that a slit or a hole is formed in the electrode 18, a projection66 is formed on the substrate in the slit or hole, and then the verticalalignment layer 20 is formed on the electrode 18. The width of thedot-projection 62 a is 3 μm, the length 8 μm, and the height 1.5 μm. Theprojection 66 formed of an acrylic resin. As projection forming means,the material of the bus line or the dielectric layer can be selectivelyused for the TFT substrate. For the CF substrate, on the other hand, thematerial of a color filter layer, a black mask layer or an overcoatlayer can be selectively used.

Also, in place of providing the projection 66, a slit or a hole may beformed as a depression in the substrate, so that means 62 for formingthe boundary of alignment of the liquid crystal molecules at apredetermined position can be a slit structure. For the TFT substrate,on the other hand, a contact hole can be selectively formed as adepression. In the case of the CF substrate, on the other hand, adepression can be formed selectively in the color filter layer, theblack mask layer or the overcoat layer.

FIG. 49 is a view showing a modification of the control means for theboundary of alignment and the linearly arranged structures. According tothis embodiment, the means 62 for forming the boundary of alignment ofthe liquid crystal molecules at a predetermined position is adot-projection 62 a. The means 62 is such that a projection 68 is formedon the substrate 12, an electrode 18 is formed, and then a verticalalignment layer 20 is formed. The means 62 can also be formed of a slitstructure by forming a depression in the substrate 12.

FIG. 50 is a view showing a modification of the control means for theboundary of alignment and the linearly arranged structures. In FIGS. 43to 49, the linearly arranged structures are configured of theprojections 30 and 32. As an alternative, the linearly arrangedstructures can be formed of the slit structures 44 and 46 (FIGS. 7 and8). In this embodiment, the linearly arranged structures are formed ofthe slit structures 46, and the means 62 for forming the boundary ofalignment of the liquid crystal molecules at a predetermined position isconfigured of the dot-projection 62 a. The means 62 is such that theprojection 68 is formed on the substrate 12, the electrode 18 is formedand then the vertical alignment layer 20 is formed.

FIG. 51 is a view showing a modification of the control means forboundary of alignment and the linearly arranged structures. In FIGS. 52and 53 are cross-sectional views. In this case, the projections 30 and32 are provides in a bent form, as the linearly arranged structures. Asdescribed above, it is necessary to take into account the effect of theoblique electric field from the edge of the pixel electrode 22 of theTFT substrate onto the opposed electrode 18. In this case, among thewedge-shaped declinations formed on the projection 32 of the TFTsubstrate, the disclination nearest to the edge of the pixel electrodehas the intensity s=−1, which corresponds to the boundary of second type(II) in FIG. 28. Among the wedge-type declinations formed on theprojection of the CF substrate, on the other hand, the declinationnearest to the edge of the pixel electrode has the intensity s=+1, whichcorresponds to the boundary of first type (I) of FIG. 28. In anapplication to an actual liquid crystal panel, the direction ofalignment on the projections 30 and 32 is determined in accordance withthe formation of the disclination by the edge of the pixel electrode 22,thereby making it possible to control all the domains in the pixel in astable fashion.

In this embodiment, the electrode located at the portion, in opposedrelation to the projection 30 of the CF substrate, is selectivelyprotruded to constitute the means 64 for forming the boundary ofalignment of the liquid crystal molecules at a predetermined position.Also, the portion in opposed relation to the projection 32 of the TFTsubstrate is selectively formed with a projection, thereby constitutingthe means 62 for forming the boundary of alignment of the liquid crystalmolecules at a predetermined position. Further, in the case where aplurality of wedge-shaped declinations are arranged on one projection inthe pixel, the alignment control means is provided to arrange thedisclinations of s=−1 and s=+1 alternately. According to thisembodiment, as shown in FIG. 53, the means 62 with the electrode 22protruded above the projection 68 and the means 62 with the projection69 protruded above the electrode 22 are arranged alternately with eachother.

FIGS. 54 and 55 are views showing a modification of the control meansfor the boundary of alignment and the linearly arranged structures. Inthis embodiment, the means 62 for forming the boundary of alignment ofthe liquid crystal molecules at a predetermined position is formed as aslit 71 in the projection 70 extending long on the upper substrate 12 inopposed relation to the projection 32 of the lower substrate. Theprojection 70 is arranged on the electrode 18 and narrower than theprojection 32.

FIGS. 56 and 57 are views showing a modification of the control meansfor orientation the boundary of alignment and the linearly arrangedstructures. In this embodiment, the means 62 for forming the boundary ofalignment of the liquid crystal molecules at a predetermined position isformed as a slit 71 in the projection 70 extending long on the uppersubstrate 12 in opposed relation to the projection 32 of the lowersubstrate and a slit 72 of the electrode 18. The projection 70 isarranged on the electrode 18 and narrower than the projection 32.

FIGS. 135A to 157D are views showing examples of auxiliary structuresfor forming the disclinations of s=+1 and s=−1, where one of thesubstrate has the alignment control structures and the other substratehas the auxiliary structures at positions opposite to the alignmentcontrol structures. The alignment control structures of the substratecan be projections or slits.

Examples of means for realizing s=−1 are shown in FIGS. 135A to 147B,and summarized as follows: Dot-projection (FIGS. 135A and 135B); Dot-cutout in electrode (FIGS. 136A and 136B); Dot-recess in electrode (FIGS.137A and 137B); Narrow linear projection and partial cut out inelectrode under the narrow projection (FIGS. 138A to 138E); Narrowlinear projection and partial enlarged portion on the narrow projection(FIGS. 139A and 139B); Narrow linear projection and partial higherportion on the narrow projection (FIGS. 140A and 140B); Narrow linearelectrode projection and partial lower portion on the narrow electrodeprojection (FIGS. 141A to 141D); Narrow linear electrode projection andpartial cut out in the electrode (FIGS. 142A to 142D); Narrow linearelectrode projection and partial narrow portion (FIGS. 143A to 143D);Narrow linear electrode projection and partial lower portion (FIGS. 144Aand 144B); Narrow linear electrode recess and partial lower portion(FIGS. 145A and 145B); and Narrow linear electrode recess and partialenlarged portion (FIGS. 146A to 146D).

Examples of means for realizing s=+1 are as follows, as shown in FIGS.147A to 157D. Dot-projection of electrode (FIGS. 147A and 147B); Narrowlinear projection and partial separation (FIGS. 148A and 148B); Narrowlinear projection and partial narrow portion (FIGS. 149A and 149B);Narrow linear projection and partial lower portion (FIGS. 150A and150B); Narrow linear slit and partial connection (FIGS. 151A and 151B);Narrow linear slit and partial narrow portion (FIGS. 152A to 152D);Narrow linear slit and partial lower portion (FIGS. 153A to 153D);Narrow linear electrode projection and partial enlarged portion (FIGS.154A to 154D); Narrow linear electrode projection and partial higherportion (FIGS. 155A and 155B); Narrow linear electrode recess andpartial higher portion (FIGS. 156A and 156B); and Narrow linearelectrode recess and partial narrow portion (FIGS. 157A to 157D).

FIG. 58 is a plan view showing the linearly arranged structuresaccording to the fourth embodiment of the present invention. FIG. 59 isa cross-sectional view of the liquid crystal display apparatus takenalong the line 59-59 in FIG. 58. The basic configuration of this liquidcrystal display apparatus 10 is similar to the basic configuration ofthe liquid crystal display apparatus 10 according to the embodimentsshown in FIG. 1 to 5. In this embodiment, the projections (alignmentcontrol structures) 30 and 32 are each formed of a plurality ofconstituent units 30 a and 32 a, respectively. As viewed from thedirection normal to one substrate, the constituent units of the linearlyarranged structure of the one substrate and the constituent units of thelinearly arranged structure of the other substrate are arrangedalternately on one line.

Taking the constituent units of the projection on the upper line (line59-59) in FIG. 58, as examples, the constituent units 30 a of theprojection 30 on the upper substrate 12 and the constituent units 32 aof the projection 32 of the lower substrate 14 are alternately arrangedon the particular line. FIG. 59 shows the constituent units 30 a and 32a. As shown in FIG. 59, the liquid crystal molecules located on thisline fall continuously in the direction parallel to the line. Asexplained with reference to FIG. 11, therefore, the problem that theliquid crystal molecules on the projection fall in random directions canbe solved.

Noting the left half portion in FIG. 58, the relative positions of theconstituent units 32 a of the projection 32 of the lower substrate 14 onthe upper line, the constituent units 30 a of the projection 30 of theupper substrate 12 on the intermediate line, and the constituent units32 a of the projection 32 of the lower substrate 14 on the lower line,are the same as the arrangement of FIGS. 3 and 4. The relative positionsare the same as in the case where these projections are in opposedrelationship in a plane at an angle to the substrate surface as shown inFIG. 2. This is also the case with FIG. 58. Thus, the operation of thisliquid crystal display apparatus is basically the same as the operationof the first embodiment. Especially, with this configuration, theresponse speed for a half tone can be improved. By the way, theconfiguration of FIG. 58 is similar to that of FIG. 20.

FIGS. 60 and 61 are diagrams views a modification of the linearlyarranged structures. In this case, the projection 30 is used as alinearly arranged structure of the upper substrate 12, while the slitstructure 46 is used as a linearly arranged structure of the lowersubstrate 14. The slit structure 46 can be divided into the constituentunits 46 a as shown in FIG. 61. In this case, the electrical connectionof the individual pixel electrodes separated by the slits can berealized with a larger width thereby leading to the advantage of a widerdesign margin. Another advantage is that there is no likelihood ofdisconnection or resistance increase in the connector between the slitsof the pixel electrode 22.

In this example, each linearly arranged structure has a plurality ofconstituent units in one pixel and a linear wall structure is arrangedsubstantially symmetrically in one pixel. A similar feature is obtainedalso in the application to the bent linearly arranged structures shownin FIG. 21.

FIG. 62 is a view showing a modification of the linearly arrangedstructure. In this case, the constituent units 30 a and 32 a of theprojections 30, 32 are arranged alternately as in the case shown in FIG.58, and at the same time, means 74 is provided for forming the boundaryof alignment in such a manner that at least one of the constituent units30 a and 32 a of the projections 30 and 32 has the liquid crystalmolecules around a point directed toward said point. The means 74 forforming the boundary of alignment is analogous, for example, to themeans 56 for forming the boundary of alignment of first type (I) shownin FIG. 28. The alignment of first type (I) forms a singularity point ofthe alignment vector corresponding to s=1. In this case, the alignmentvector of the minor domains on the projection can be controlled, withthe result that the stable control of the display domains is realizedfor an improved response speed for a half tone.

The means 74 can be similar to the corresponding one of the secondembodiment described above.

FIG. 63 shows a specific example of the means 74 for forming theboundary of alignment. In FIG. 63, the means 74 is to enlarge the widthof the constituent units 30 a and 32 a of the projections 30 and 32.

Also, as shown in FIG. 64, the means 74 can also be achieved byincreasing the height of the constituent units 30 a and 32 a of theprojections 30 and 32.

At a point where the width of the constituent units 30 a and 32 a of theprojection is partially increased or the height is increased, the liquidcrystal director widens from the particular part as a center andtherefore the particular point constitutes a singularity point of s=1.Also, in the case where the common substrate is arranged on this side,the liquid crystal director toward the center of the pixel from the edgeof the pixel electrode rises toward the center on all the projectionsdue to the oblique electric field of the pixel electrode. Thus, it ispossible to form a minor domain which is continuously connected smoothlyin the projection boundary.

FIG. 65 shows a specific example of the means 74 for forming theboundary of alignment. In FIG. 65, the linearly arranged structures arecombination of the projections 32 and the slit structures 44. The means74 can be achieved by increasing the width or height of the constituentunits 32 a of the projection 32 and by increasing the width or depth ofthe slit structure 44.

The response speed as compared with the corresponding speed in thestructures of the first embodiment is shown in Table 2 (slit width 10μm, projection width 10 μm and distance 20 μm between projections).

TABLE 2 1st embodiment 4th embodiment Drive condition T_(on) + T_(off)25 ms −25 ms 0 to 5 V T_(on) + T_(off) 50 ms −40 ms 0 to 3 V

In this way, the response speed can be improved by the smooth motion ofthe minor domains on the projections. Thus, the improvement of theresponse for a half tone with a stable orientation can be assured. Also,the width of the electrical connector of the slits can be increased,leading to the advantage that there is no fear of disconnection.

This embodiment was explained with reference to two divisions as anexample. The same can be applied to the bent type linearly arrangedstructures. Also, several embodiments can be combined.

FIG. 66 is a plan view showing the linearly arranged structuresaccording to the fifth embodiment of the present invention. The basicconfiguration of this liquid crystal display apparatus 10 is similar tothat of the liquid crystal display apparatus 10 according to theembodiments of FIGS. 1, 2 and 5. In the embodiment of FIG. 5, theprojections (linearly arranged structure) 30 and 32 extend parallel toeach other and are bent. With this configuration, one pixel includesfour areas of alignment of the liquid crystal molecules 16C, 16D, 16Eand 16F, oriented in thereby making possible the alignment division witha superior visual angle characteristic.

The two line segments forming the bent portion of the projections 30 and32 are at an angle of 90 degrees. The polarizers 26 and 28 are arrangedin such a manner that the polarization axes form an angle of 45 degreesto the line segments of the bent portion of the projections 30 and 32,as designated by 48. Although only a part of the liquid crystalmolecules is shown in FIG. 66, there are four areas of alignment of theliquid crystal molecules 16C, 16D, 16E and 16F (FIG. 5) in one pixel.

In this embodiment, additional projections 76 and 78 constitutingadditional linear wall structures are arranged on the obtuse angle sideof the bent portions of the substrates having the projections 30 and 32.Specifically, the additional projection 76 is arranged continuously fromthe projection 30 on the obtuse angle side of the projection 30 of theupper substrate 12. The additional projection 76 extends along thebisector of the obtuse angle on the obtuse angle side of the projection30 of the upper substrate 12. On the other hand, the additionalprojection 78 is arranged continuously from the projection 32 on theobtuse angle side of the projection 32 of the lower substrate 14. Theadditional projection 78 extends along the bisector of the obtuse angleon the particular obtuse angle side of the projection 32 of the lowersubstrate 14. As a result” the brightness is improved for a higherresponse.

FIG. 67 shows projections 30 and 32 similar to the corresponding ones inFIG. 5. FIG. 67 shows in more detail the alignment of the liquid crystalmolecules with respect to the projections 30 and 32. One pixel containsfour areas of alignment of the liquid crystal molecules 16C, 16D, 16Eand 16F. Further, there is an area of liquid crystal molecules 16G onthe obtuse angle side of the bent portion of the projection 30, andliquid crystal molecules 16H on the obtuse angle side of the bentportion of the projection 32. At the time of voltage application, theliquid crystal molecules should lie in the direction perpendicular tothe projections 30 and 32, respectively. At the bent portions of theprojections 30 and 32, however, the liquid crystal molecules are alignedin such a manner that the liquid crystal molecules 16G and 16H arealigned in parallel along the bisector of the obtuse angle of the bentportions of the projections 30 and 32 since the liquid crystal molecules16D-16F and 16C-16E located on the two line segments forming the bentportions are aligned continuously. The direction of alignment of theliquid crystal molecules 16G and 16H is parallel or perpendicular to thepolarization axes indicated by 48, and in the case where a white displayis formed by applying a voltage, the areas of the liquid crystalmolecules 16G and 16H become dark.

FIG. 68 shows a screen when a white display is viewed on the liquidcrystal display apparatus having the linearly arranged structures ofFIG. 67. The areas G and H of the liquid crystal molecules 16G and 16Hactually darken. Also, the areas I at the edges of the pixel electrodes22 darken. This will be explained later.

In FIG. 66, the additional projections 76 and 78 are formed on theobtuse angle side of the bent portions of the substrates having theprojections 30 and 32, and therefore # the alignment of the liquidcrystal molecules 16G and 16H in question is corrected to realize almostthe same alignment as the liquid crystal molecules 16D-16F and 16C-16Elocated on both sides thereof. As a result, the areas G and H shown inFIG. 68 are not darkened and the brightness is improved.

The width of the additional projections 76 and 78 can be the same as thewidth of the original projections 30 and 32. Nevertheless, the width ofthe additional projections 76 and 78 is desirably smaller than the widthof the original projections 30 and 32. This is by reason of the factthat, if the additional projections 76 and 78 have a strong power forcontrolling the alignment, the neighboring liquid crystal molecules cometo be aligned perpendicular to the additional projections 76 and 78.

If the additional projections have only a small power for controllingthe alignment, on the other hand, the neighboring liquid crystalmolecules are not aligned perpendicular to the additional projections 76and 78 but assume the almost the same alignment as the liquid crystalmolecules 16D-16F and 16C-16E located on both sides thereof. In the casewhere the width of the original projections 30 and 32 is 10 μm, forexample, the desirable width of the additional projections 76 and 78 maybe about 5 μm.

By forming the additional projections 76 and 78 on the projections 30and 32 as described above, the manner in which the liquid crystalmolecules at the bent portion fall can be definitely determined, andtherefore both the brightness and the response can be improved.

In this embodiment, the glass substrates 12 and 14 are made of NA-35 inthe thickness of 0.7 mm. The pixel electrodes 22 and the commonelectrode 18 are made of ITO. TFTs for driving the liquid crystal andbus lines are arranged on the substrate having the pixel electrodes 22,while a color filter is arranged on the opposed substrate having thecommon electrode 18. The photosensitive acrylic material PC-335 (made byJSR) is used for the projections. For both the substrates, theprojection width is 10 μm and the projection interval (the distance fromthe projection end of one substrate to the projection end of the othersubstrate after attaching the two substrates to each other) is 30 μm.The projection height is 1.5 μm. The vertical alignment layers 20, 24are made of JALS-204 (made by JSR). The liquid crystal material ofMJ95785 (made by Merc) is used. The spacer is Microbar having a diameterof 3.5 μm (made by Sekisui Fine Chemical).

FIG. 69 shows a modification of the linearly arranged structures. Inthis example, additional projections 76 x and 78 x are arranged on theacute angle side of the bent portions of the projections 30 and 32. Inthis case, alignment of the liquid crystal molecules controlled by theprojections 30, 32 is not smoothly connected to alignment of the liquidcrystal molecules controlled by the additional projections 76 x and 78x. Thus, the liquid crystal molecules in the neighborhood of the bentportions of the projections 30 and 32 are aligned in the direction atright angles or perpendicular to the direction of the polarization axes,resulting in an insufficient improvement. It has been found, therefore,that the additional projections 76 x and 78 x are preferably arranged onthe obtuse angle side of the bent portions of the projections 30 and 32,as shown in FIG. 66.

The additional projections 76 and 78 have thus far been explained asviewed from the same substrate as the one having the projections 30 and32. When viewed from the substrate opposed to the one formed with theprojections 30 and 32, the additional projections 76 and 78 assume thefollowing form. In FIG. 66, for example, the additional projection 76 isformed on the acute angle side of the bent portion of the projection 32of the substrate 14 in opposed relationship to the substrate 12 havingthe projections 30. In a similar fashion, the additional projection 78is formed on the acute angle side of the bent portion of the projection30 of the substrate 12 in opposed relationship to the substrate 14having the projections 32.

FIG. 70 shows a modification of the linearly arranged structures. Inthis example, as in the example of FIG. 66, the additional projections76 and 78 are formed on the obtuse angle side of the bent portions ofthe projections 30 and 32. The projections 76 and 78 in this exampleextend further than the projections 76 and 78 of FIG. 66. The forwardend of each of the additional projections 76 and 78 extends to a pointwhere it is overlapped with the bent portions of the projections 32 and30 in opposed relationship thereto. The additional projections 76 and 78may be extended in this way but are not desirably extended beyond thepoint where the forward end thereof is overlapped with the bent portionsof the projections 32 and 30.

Further, in this example, the upper substrate 12 and the lower substrateformed with the projections 32 and 30 and the additional projections 76and 78 are attached to each other with the peripheral portions thereofsealed. Thus, an empty panel is formed, into which the liquid crystal isinjected subsequently. In this example, the height of the projections is1.75 μm, and the projections of the substrates partially contact witheach other, so that the cell thickness of 3.5 μm is secured. The cellthickness can be maintained by partial contact between the projectionsof the two substrates, without using spacers. If a spacer is inserted,the orientation of the liquid crystal molecules would be affected alsoon the surface of the spacer. In this arrangement, there is no spacer,and any abnormal alignment which otherwise might be caused by spacers iseliminated.

As described above, the linearly arranged structures for controlling-thealignment is configured of the projections 30 and 32 or the slitstructures 44 and 46. In the case where the slit structures 44 and 46are employed as linearly arranged structures, additional slit structuressimilar to the slit structures 44 and 46 are provided in place of theadditional projections 76 and 78. Also, the linearly arranged structuresfor controlling the alignment may be configured of projections on slitswhich are formed in the electrode.

FIG. 71 shows a modification of the linearly arranged structures. As thelinearly arranged structures for controlling the alignment, theprojections 30 of the upper substrate 12 and the slit structures 46 ofthe lower substrate 14 are provided. As described above, the slitstructures 46 are configured by forming slits in the pixel electrodes 22of the lower substrate 14. The additional projection 76 is provided in asimilar manner to the additional projection 76 of FIG. 66, and theadditional slit structure 78 y is provided on the obtuse angle side ofthe bent portion of the slit structure 46 in place of the additionalprojection 78 of FIG. 66. The additional slit structure 78 y is notconnected to the bent portion of the slit structure 46 by reason of thefact that the slit has a discontinuous portion as the slit structure 46is configured as a slit in the pixel electrode 22. By the way, theadditional slit structure 78 y can be said to be provided on the acuteangle side of the projection 30 of the opposed substrate.

FIG. 72 shows a modification of the linearly arranged structures. Inthis example, as in the case of FIG. 66, the additional projections 76and 78 are provided. Further, the edge projections 80 are provided atpoints where they are overlapped with at least a part of the edge of thepixel electrode 22. In such a case, the projections 30 and 32 arearranged neither in parallel nor perpendicular to the edge of the pixelelectrode 22. The edge projections 80 are arranged at positionscorresponding to the areas I of FIG. 68. As shown in FIG. 67, the liquidcrystal molecules are aligned in such a manner as to fall toward thecenter of the pixel under the effect of the oblique electric field atthe edge of the pixel electrode 22. At the positions corresponding tothe areas I of FIG. 68, the projection 30 on the upper substrate(opposed substrate) 12 and the edge of the pixel electrode 22 form anobtuse angle, or the projection 32 on the pixel electrode 22 and theedge of the pixel electrode 22 assumes an acute angle.

In these areas, the alignment of the liquid crystal molecules isconsiderably different from the alignment of the liquid crystalmolecules located inward of the edge (FIG. 67), and therefore thedisplay becomes dark as shown in FIG. 68. Provision of the edgeprojections 80 as shown in FIG. 72, however, causes the alignment of theliquid crystal molecules at the edge of the pixel electrode 22 to becomesimilar to the alignment of the liquid crystal molecules located inwardof the particular edge, thereby preventing the display from darkening.In FIG. 72, corner projections 82 are also provided.

FIG. 73 shows a modification of the linearly arranged structures. Thismodification is similar to the modification of FIG. 72 except that thecorner projections 82 are not included in this modification. Also in thecases of FIGS. 72 and 73, a newly formed projection is extended to theprojection on the pixel electrode. The height of the projection is 1.75μm and no spacer is sprayed. The cell thickness of 3.5 μm is secured bypartial contact between the projections of the two substrates.

FIG. 74 shows a modification of the linearly arranged structures. Inthis modification, the projection 30 has an additional projection 76. Atthe same time, the projection 30 and the slit structure 46 areconfigured of a plurality of constituent units (30S and 46S) as in thecase of FIG. 21. In this case, therefore, the effect of configuring thelinearly arranged structures of a plurality of constituent units and theeffect of providing an additional linear wall structure are bothobtained.

FIG. 75 is a view showing the relationship between the linearly arrangedstructures and polarizers of a liquid crystal display apparatusaccording to the sixth embodiment of the present invention. FIG. 76 is aview showing the display brightness in the configuration of FIG. 75.

The liquid crystal display apparatus shown in FIG. 75 includes aconfiguration basically similar to that of the liquid crystal displayapparatuses shown in FIGS. 1 to 10. Specifically, the liquid crystaldisplay apparatus comprises a pair of substrates 12 and 14, a liquidcrystal 16 having a negative anisotropy of its dielectric constant andinserted between the pair of the substrates 12 and 14, linearly arrangedstructures (projections 30 and 32, slits 44 and 46, for example)provided on each of the pair of substrates 12 and 14 for controlling thealignment of the liquid crystal 16 and polarizers 26 and 28 arranged onthe outside of the pair of substrates 12 and 14, respectively. The pairof substrates 12 and 14 include the electrodes 18 and 22 and thevertical alignment layers 20 and 24, respectively.

The linear wall structure for controlling the alignment of the liquidcrystal in FIG. 75 is configured of projections similar to theprojections 30 and 32 shown in FIG. 4. The arrangement of the polarizers26 and 28 is shown by numeral 48. The polarizers 26 and 28 haveabsorption axes 26 a and 28 a, respectively. These absorption axes 26 aand 28 a cross at right angles to each other. The absorption axis 26 aof one polarizer 26 (hence, also the absorption axis 28 a of the otherpolarizer 28) is arranged at a predetermined angle (a) displaced fromthe orientation rotated by 45 degrees from the orientation in which theprojections 30 and 32 extend. To express it in more easily understoodterms, in FIG. 75, the absorption axis 26 a of the polarizer 26 isarranged at an angle (45°±a) to the straight line (indicated by dashedline) crossing at right angles to the projections 30 and 32, and henceat an angle (45°±a) to the orientation in which the projections 30 and32 extend.

FIG. 75 shows the behavior of the liquid crystal molecules on thelinearly arranged structures (projections 30 and 32) for controlling theorientation of the liquid crystal. In a liquid crystal display apparatushaving the linearly arranged structures (projections 30 and 32, slits 44and 46) for controlling the alignment of the liquid crystal, asexplained above with reference to FIGS. 11 and 13, an overshoot occursimmediately after voltage application. One of the causes of theovershoot is that in the case where the polarizers 26 and 28 arearranged at 45° to the linearly arranged structures, the liquid crystalmolecules fail to be arranged in a position exactly perpendicular to thelinearly arranged structures after voltage application and therefore thebrightness of white display is reduced. This embodiment is intended tosolve such a problem.

In FIG. 75, upon application of a voltage thereto, the liquid crystalmolecules located between the projections 30 and 32 fall into a positionperpendicular to the projections 30 and 32. The liquid crystal moleculeson the projections 30 and 32 fall rightward or leftward in parallel tothe projections 30 and 32. As a result, the liquid crystal moleculeslocated between the projections 30 and 32 do not assume a positionexactly perpendicular to the projections 30 and 32 but a positionsomewhat oblique to the projections 30 and 32. By way of explanation,the left area L and the right area R are shown distinctly in FIG. 75.The liquid crystal molecules located in the left area L are rotatedclockwise at an angle g to the line perpendicular to the projections 30and 32 (the director of the liquid crystal for the left area L is theangle g), while the liquid crystal molecules located in the right area Rare rotated counterclockwise.

In this embodiment, the polarizers 26 and 28 are arranged in accordancewith the alignment of the liquid crystal molecules located in the leftarea L. The absorption axis 26 a of the polarizer 26 is arranged at anangle of 45° to the director of the liquid crystal located in the leftarea L. Thus, as shown in FIG. 76A, the brightest display can berealized at the time of white display in the left area L.

In the right area R, on the other hand, the same condition as realizedin the left area L cannot be realized. Instead, as shown in FIG. 76B,the brightest display cannot be realized at the time of white display.As shown in FIG. 76C, however, as far as the entire display (L+R)combining the bright left area L and the right area R which darkensafter being brightened once, a bright-display can be realized at thetime of white display, thereby making it possible to improve theovershoot considerably.

FIG. 77 is a view showing the relationship between the director angle aof the liquid crystal and the frequency thereof for each minor area in aliquid crystal display apparatus having linearly arranged structures(projections 30 and 32, for example) for controlling the alignment ofthe liquid crystal. This indicates that the director of the liquidcrystal becomes oblique generally in the range not more than 20°.Therefore, the predetermined angle a by which the absorption axis 26 aof the polarizer 26 is displaced from the orientation rotated by 45degrees from the orientation in which the projections 30 and 32 extendis not more than 20°.

In this case, the crossing angle b, which is assumed to be the angle atwhich the direction of the absorption axis 26 a of the polarizer 26crosses the linearly arranged structures (projections 30 and 32, forexample), is in the range of 25°<b<45° or 45°<b<65°. Between thepolarizers 26 and 28 and the substrates 12 and 14, however, there is anerror of about 2° derived from the relative positions at the time ofmanufacture. Taking this into account, the crossing angle b should be inthe range of 25°<b<43° or 47°<b<58°.

More specifically, in FIG. 77, the frequency of the director of theliquid crystal is high in the range of 2° to 13°. Therefore thepredetermined angle a is desirably in the range between 2° and 13°. Inthis case, the crossing angle b should be in the range of 32°<b<43° or47°<b<58°.

FIGS. 78 and 79 show a modification of the embodiment of FIG. 75. FIG.78 is a view showing the relationship between the linearly arrangedstructures and the polarizers of a liquid crystal display apparatus, andFIG. 79 is a cross-sectional view of the liquid crystal displayapparatus shown in FIG. 78. The upper substrate 12 has projections 30,and the lower substrate 14 has projections 32. The projections 30 and 32have square bent portions. In this case, the absorption axis 26 a of thepolarizer 26 is arranged at an angle of 55° to the line sections of theprojections 30. The absorption axes 26 a and 28 a of the two polarizers26 and 28 cross at right angles to each other.

FIGS. 80 and 81 are views showing a modification of the embodiment ofFIG. 75. FIG. 80 is a view showing the relationship between the linearlyarranged structures and the polarizers of the liquid crystal displayapparatus, and FIG. 81 is a cross-sectional view of the liquid crystaldisplay apparatus of FIG. 80. The upper substrate 12 has projections 30,and the lower substrate 14 has slits 46. The projections 30 and theslits 46 have square bent portions. In this case, the absorption axis 26a of the polarizer 26 is arranged at an angle of 55° to the linesections of the projection 30 (or the slit 46). The absorption axes 26 aand 28 a of the two polarizers 26 and 28 cross at right angles to eachother.

FIG. 82 is a view showing the linearly arranged structures of the liquidcrystal display apparatus according to the seventh embodiment of thepresent invention. FIG. 83 is a cross-sectional view of the liquidcrystal display apparatus of FIG. 82.

The liquid crystal display apparatus shown in FIGS. 82 and 83 comprisesa pair of substrates 12 and 14, a liquid crystal having a negativeanisotropy of its dielectric constant and inserted between the pair ofthe substrates 12 and 14, linearly arranged structures (projections 30and 32 or slits 44 and 46, for example) arranged on each of the pair ofthe substrates 12 and 14 for controlling the alignment of the liquidcrystal 16, and polarizers 26 and 28 arranged on the outside of the pairof the substrates 12 and 14, respectively.

The lower substrate 14 is a TFT substrate, and the electrode 22 is pixelelectrodes. The lower substrate 14 has TFTs 40 connected to the pixelelectrode 22. The TFT 40 is connected to a gate bus line and a drain busline (FIG. 3). A shielding area 84 covers the TFT 40 and theneighborhood thereof. The shielding area 84 is provided for preventingthe TFT 40 from being exposed to direct light. The TFT 40 is in contactwith the pixel electrode 22 and therefore the shielding area 84 ispartially overlapped with the pixel electrode 22.

The pixel electrode 22 defines a pixel aperture. However, the areaoccupied by the pixel electrode 22 but not overlapped with the shieldingarea 84 is not a pixel aperture. Thus, that portion of the area occupiedby the pixel electrode 22 and not overlapped with the shielding area 84constitutes a non-shielding area (pixel aperture).

In this example, the linearly arranged structures arranged on the uppersubstrate 12 are the projections 30, and the linearly arrangedstructures arranged on the lower substrate 14 are the slits 46 formed onthe electrode 22. The projections 30 and the slits 46 are formed to havebent portions. Examples of combination of the projections 30 and theslits 46 are shown in FIGS. 71 and 74.

The shielding area 84 and the linearly arranged structures 30 and 46 arearranged in such a manner that the shielding area 84 and a part of thelinearly arranged structure 30 are partially overlapped to reduce thearea of the linearly arranged structure 30 and 46 arranged in thenon-shielding area.

As described above, the projection 30 is formed of a transparentdielectric material, and the slit 46 is formed in a transparent pixelelectrode 22. Therefore, the linearly arranged structure 30 and 47 canbe regarded as transparent members. Nevertheless, in view of the factthat the liquid crystal molecules located on the linearly arrangedstructures 30 and 47 are aligned differently than the liquid crystalmolecules located in the gap between the linearly arranged structure 30and 47 upon application of a voltage thereto, the light transmissionrate and the opening rate are reduced on the linearly arranged structure30 and 47 in the pixel aperture at the time of white display uponapplication of a voltage thereto. Thus, the area of the linearlyarranged structures 30 and 46 arranged in the non-shielding area (thepixel aperture) is desirably reduced. A predetermined area is requiredof the linearly arranged structures 30 and 46, however, for controllingthe alignment of the liquid crystal. In view of this, assuming that thearea of the linearly arranged structures 30 and 46 is constant, a partof the linearly arranged structures 30 and 46 is relocated to a positionoverlapped with the shielding area 84 to reduce the area of the linearlyarranged structures 30 and 46 arranged in the non-shielding area. Inthis way, the actual aperture rate can be increased. For this reason, inFIG. 82, the shielding area 84 and the linearly arranged structures 30and 46 are designed in such a manner that the projection 30 is partiallyoverlapped with the shielding area 84.

FIG. 84 is a view showing a specific example of the linearly arrangedstructures 30 and 46 of FIG. 82. The feature of the apparatus shown inFIG. 84 is similar to that of the apparatus explained with reference toFIG. 82. The source electrode of the TFT 40 is connected to the pixelelectrode 22 by a contact hole 40 h.

Further, as shown in FIGS. 82 to 84, in the case where the linearlyarranged structures of the substrate 14 having the TFTs 40 are slits 46,the projections 30 (or the slits 44) of the opposed substrate 12 isdesirably overlapped with the shielding area 84 covering the TFT 40. Theslit 46 overlapped with the shielding area 84 may make it inconvenientto establish the contact between the TFT 40 and the pixel electrode 22.

FIG. 85 is a view showing a comparative example of the linearly arrangedstructures of FIG. 82. In this example, in the case where the linearlyarranged structures of the substrate 14 having the TFTs 40 are the slits46, the TFT substrate 14 or the slit 46 is arranged to be overlappedwith the shielding area 84 covering the TFT 40. Once the slit 46 isoverlapped with the shielding area 84, however, it becomes difficult toconnect the TFT 40 and the pixel electrode 22. In other words, the slit46 comes to occupy the position where a contact hole (40 h in FIG. 84)is not to be formed.

FIG. 86 is a view showing a modification of the linearly arrangedstructures of FIG. 28, and FIG. 87 is a cross-sectional view of theliquid crystal display apparatus having the linearly arranged structureof FIG. 86. FIGS. 86 and 87 are views for explaining an example in whichthe electrode is removed from under the third projection in the leftcolumn of Table 1 described above. The projection 32 is formed on theelectrode 22 of the substrate 14, but the electrode 22 under theprojection 32 is formed with a rhombic void 22 x. The projection 32 canconstitute the boundary forming means 56 of first type (I) due to thevoid 22 x of the electrode 22. The void 22 x is not necessarily rhombicbut may take other shapes such as rectangle.

FIG. 88 is a view showing the linearly arranged structures of the liquidcrystal display apparatus according to an eighth embodiment of theinvention. FIG. 89 is a cross-sectional view of the liquid crystaldisplay apparatus having the linearly arranged structures of FIG. 88.The embodiment of FIGS. 88 and 89 has a combined feature of theembodiment of FIG. 28 and the embodiment of FIG. 43. Specifically, thisembodiment comprises first means for forming the boundary of alignmentof the liquid crystal in the linearly arranged structures of onesubstrate, and second means for forming the boundary of alignment of theliquid crystal at the same position as the first means in the othersubstrate along the extension of the linearly arranged structures.

The upper substrate 12 has the linearly arranged structures 30 formed ofprojections, and the lower substrate 14 has the linearly arrangedstructures 32 formed of projections. FIG. 89 is a cross-sectional viewtaken along a line passing through the linearly arranged structures 32formed of the projections of the lower substrate 14. The projection 32has separation sections 32T, thereby forming the boundary forming means58 of second type (II) on the projection 32. Further, the opposedsubstrate 12 is formed with dot-projections 62 a at positions opposed tothe separation sections 32T, respectively. As explained with referenceto FIG. 43, the dot-projections 62 a of the opposed substrate 12 aremeans 62 for forming the boundary of alignment of the liquid crystalmolecules at a predetermined position and have the same function ofcontrolling the liquid crystal alignment as the boundary forming means58 of second type (II). In this case, therefore, the two boundaryforming means 58 and 62 of second type (II) are arranged at the sameposition thereby to secure the formation of the boundary of second type(II) more positively. Thus, the alignment of the liquid crystalmolecules is assured further.

FIGS. 90 and 91 are views showing an example analogous to FIGS. 88 and89. This modification also includes the boundary forming means 58 ofsecond type (II), and the opposed substrate 12 includes the means 62 forforming the boundary of alignment of the liquid crystal molecules at apredetermined position. In the embodiment of FIGS. 90 and 91, the sizerelationship between the separation sections 32T of the projection 32constituting the means 58 and the projections 62 a constituting themeans 62 is different from the corresponding relation in FIGS. 88 and89.

FIG. 92 is a view showing a modification of the linearly arrangedstructures of FIG. 88. FIG. 93 is a cross-sectional view showing thelinear wall structure (projection) 32 of FIG. 92. This linearly arrangedstructure (projections) 32 includes the boundary forming means 56 offirst type (I) formed by increasing the height of the projection 32 andthe boundary forming means 58 of second type (II) formed by reducing theheight of the projection 32 as shown in FIG. 32. The opposed substrate12 includes the boundary forming means 62 at the same position as themeans 56, 58.

FIG. 94 is a view showing a modification of the linearly arrangedstructures of FIG. 93. This linearly arranged structures (projections)32, as shown in FIG. 35, include the boundary forming means 56 of firsttype (I) formed by widening the projection 32 and the boundary formingmeans 58 of second type (II) formed by narrowing the width of theprojection 32. The opposed substrate 12 can include the boundary formingmeans 62 at the same position as the means 56, 58.

FIGS. 95 and 96 are views showing an example similar to FIGS. 88 and 89.In this example also, the projection 32 includes the boundary formingmeans 56 of a first type (I) and the boundary forming means 58 of asecond type (II), and the opposed substrate 12 includes the means 62 forforming the boundary of alignment of the liquid crystal molecules at thesame predetermined position as the means 56 and 58. The boundary formingmeans 56 of first type (I) constitutes a separation section of theprojection 32 and the boundary forming means 58 of a second type (II)constitutes a portion increased in height on the projection 32.

FIG. 97 is a view showing a modification of the linearly arrangedstructures of FIG. 88. In this example, the linearly arranged structuresof the lower substrate 14 are formed as slits 46. The slits 46 areseparated by the walls 58 a, and constitute the boundary forming means58 of second type (II). At the same time, each wall 58 a, to cooperateas a protruded wall, constitutes the means 62 for forming the boundaryof alignment of the liquid crystal molecules at a predetermined positionon the linearly arranged structures (projections) 30.

FIG. 98 is a view showing linearly arranged structures analogous to FIG.97. In this example, the linearly arranged structures of the lowersubstrate 14 are formed as slits 46 separated by walls 58 a. The walls58 a are located at the separation sections and the intermediateportions of the component parts of the separated linear wall structure(projections) with which the walls 58 a are to cooperate, and constitutethe boundary forming means 58 of first type (I) and the boundary formingmeans 58 of second type (II). At the same time, the wall 8 a, tocooperate as a protruded wall, constitutes the means 62 for forming theboundary of alignment of the liquid crystal molecules at a predeterminedposition on the linearly arranged structures (projection) 30.

The embodiments described above with reference to FIGS. 88 to 98 can besummarized as follows. (a) As the boundary forming means 56 of firsttype (I), the projections 30 and 32 are thickened or increased in heightand the slits 44 and 46 are thickened or increased in height, while asthe boundary forming means 60 and 62 for the opposed substrate, adot-projection, a partially cut projection, a partially thinnedprojection, a partially lowered projection, a partially connectedprojection, a partially thinned slit or a partially lowered slit areprovided. (b) As the boundary forming means 58 of second type (II), theprojections 30, 32 are cut (into a plurality of constituent units),thinned or reduced in height, and the slits 44, 46 are cut, thinned orreduced in height. As the boundary forming means 60, 62 for the opposedsubstrate, on the other hand, a dotted projection, a partially thickenedprojection, a projection partially increased in height, a partiallyprotruded projection, a partially thickened projection or a dottedelectrode recess is formed.

FIG. 99 is a view showing the linearly arranged structures of the liquidcrystal display apparatus according to the ninth embodiment of thepresent invention. In this case, as in the preceding embodiment, theliquid crystal display apparatus comprises a pair of substrates 12 and14, a liquid crystal 16 having a negative anisotropy of its dielectricconstant and inserted between the pair of the substrates 12 and 14,linearly arranged structures (such as projections 30 and 32 or slits 44and 46) arranged in each of the pair of the substrates 12 and 14 forcontrolling the alignment of the liquid crystal 16, and polarizers 26and 28 arranged on the outside of the pair of the substrates 12 and 14.

FIG. 99 shows one linearly arranged structure (projection) 30 of theupper substrate 12 and one linearly arranged structure (projection) 32of the lower substrate 14. The linearly arranged structure 30 of theupper substrate includes the means 86 similar to the means 56 forforming the boundary of alignment of first type with the liquid crystalmolecules around a point are directed to said point as described abovewith reference to FIG. 28, and the linearly arranged structure 32 of thelower substrate also includes the means 86 for forming the boundary ofalignment of first type with the liquid crystal molecules around a pointare directed to said point.

At the time of voltage application, as described previously, the liquidcrystal molecules on the linearly arranged structures 30 of the uppersubstrate and the liquid crystal molecules on the linearly arrangedstructures 32 of the lower substrate are aligned in the directionparallel to the linearly arranged structure 30 and 32, respectively. Onthe other hand, the liquid crystal molecules located in the gap betweenthe linearly arranged structures 30 of the upper substrate and thelinearly arranged structures 32 of the lower substrate are alignedperpendicular to the linearly arranged structures 30 and 32.

Further, among the liquid crystal molecules on the linearly arrangedstructures 30 of the lower substrate, those liquid crystal moleculeslocated in the area on the left side of the boundary forming means 86are aligned rightward with the head thereof directed toward the boundaryforming means 86 as indicated by arrow, while the liquid crystalmolecules located in the area on the right side of the boundary formingmeans 86 are aligned leftward with the head thereof directed toward theboundary forming means 86 as indicated by arrow. In similar fashion,among the liquid crystal molecules on the linearly arranged structures32 of the lower substrate, those liquid crystal molecules located in thearea on the left side of the boundary forming means 86 are alignedleftward with the head thereof directed away from the boundary formingmeans 86 as indicated by arrow, while the liquid crystal moleculeslocated in the area on the right side of the boundary forming means 86are oriented with the head thereof directed rightward away from theboundary forming means 86 as indicated by arrow.

With regard to the liquid crystal molecules located on a lineperpendicular to the linearly arranged structures 30 and 32 (thoseliquid crystal molecules located in the area on the left side of theboundary forming means 86 surrounded by a dotted circle, for example),the liquid crystal molecules on the linearly arranged structures 30 arealigned rightward (first direction), and the liquid crystal moleculeslocated on the linearly arranged structures 32 are aligned leftward (inthe second direction opposite to the first direction). In other words,among the liquid crystal molecules located in the area on the left sideof the boundary forming means 86, those liquid crystal molecules locatedon the linearly arranged structures 30 are aligned in the directionopposite to the liquid crystal molecules located on the linearlyarranged structures 32. Similarly, among the liquid crystal moleculeslocated in the area on the right side of the boundary forming means 86,the liquid crystal molecules located on the linearly arranged structures30 are aligned in the direction opposite to the liquid crystal moleculeslocated on the linearly arranged structures 32.

FIG. 100 is a view showing a modification of the linearly arrangedstructures of FIG. 99. In this case, the linearly arranged structures 30and 32 both include means 88 similar to the means 58 for forming theboundary of alignment of second type in which part of the liquid crystalmolecules around a point are directed toward said point and the otherliquid crystal molecules are aligned in the opposite direction from thesame point with regard to the liquid crystal molecules on the linearlyarranged structures 30 of the upper substrate, therefore, those liquidcrystal molecules located in the area on the left side of the boundaryforming means 88 are aligned leftward with the head thereof directedaway from the boundary forming means 88, as indicated by arrow, whilethose liquid crystal molecules located in the area on the right side ofthe boundary forming means 88 are oriented, as indicated by arrow,rightward with the head thereof directed away from the boundary formingmeans 88. In similar fashion, among the liquid crystal molecules on thelinearly arranged structures 32 of the lower substrate, those liquidcrystal molecules located in the area on the left side of the boundaryforming means 88 are aligned, as indicated by arrow, rightward with thehead thereof directed toward the boundary forming means 88, while thoseliquid crystal molecules located in the area on the right side of theboundary forming means 88 are aligned, as indicated by arrow, leftwardwith the head thereof directed toward the boundary forming means 88.

Taking the liquid crystal molecules located on a line perpendicular tothe linearly arranged structures 30 and 32, as an example, the liquidcrystal molecules on the linearly arranged structures 30 are aligned inthe first direction, while the liquid crystal molecules on the linearlyarranged structures 32 are aligned in the second direction opposite tothe first direction.

FIG. 101 is a view for explaining the problem of operating by finger aliquid crystal display apparatus having the linearly arranged structures30 and 32. FIG. 101 shows the state in which a point D on the imagedisplay screen is pressed by a finger. In the case where the point D onthe image display screen is pressed by a finger, the trace of the fingermay be left at the point D as a display defect. The finger tracedisappears when the voltage application is stopped. Even when thevoltage application is continued, the finger trace may disappear withina short voltage application time or may remain after a protractedvoltage application. No problem is posed in the case where the liquidcrystal display apparatus is used as an apparatus in which no externalforce is applied such as by finger. For a liquid crystal displayapparatus such as a touch panel in which an external force is applied byfinger or the like, on the other hand, the problem of finger trace beingleft on the display screen is posed.

FIG. 102 is a view showing a typical example in which a finger trace isliable to occur. The linearly arranged structures 30 of the uppersubstrate includes means 86 for forming the boundary of alignment offirst type, and the linearly arranged structures 32 of the lowersubstrate includes means 88 for forming the boundary of alignment ofsecond type in which some liquid crystal molecules around a point aredirected to said point while the other liquid crystal molecules aredirected in the opposite direction from the same point. The liquidcrystal molecules on the linearly arranged structures of the uppersubstrate 30 are thus aligned in the same direction as the liquidcrystal molecules on the linearly arranged structures 32 of the lowersubstrate. Among the liquid crystal molecules on the linearly arrangedstructures 30 of the upper substrate, for example, the liquid crystalmolecules located in the area on the left side of the boundary formingmeans 86 are aligned leftward, while among the liquid crystal moleculeson the linearly arranged structures 32 of the lower substrate, theliquid crystal molecules located in the area on the left side of theboundary forming means 88 are aligned leftward.

In the case where the image display screen is pressed by finger, theliquid crystal molecules on the linearly arranged structures 30 and 32move toward the gap between the linearly arranged structures 30 and 32,so that a part 16 m of the liquid crystal molecules in the gap betweenthe linearly arranged structures 30 and 32 are aligned in the directionparallel to the linearly arranged structures 30 and 32. The liquidcrystal molecules in the gap between the linearly arranged structures 30and 32 are originally required to be perpendicular to the linearlyarranged structures 30 and 32. At the portion pressed by finger,however, the part 16 m of the liquid crystal molecules in the gapbetween the linearly arranged structures 30 and 32 is aligned parallelto the linearly arranged structures 30 and 32. Thus, a declinationoccurs resulting in the finger trace being left.

As shown in FIG. 102, in the case where the liquid crystal molecules onthe linearly arranged structures 30 and 32 of the two substrates arealigned in the same direction, the liquid crystal molecules that havemoved toward the gap between the linearly arranged structures 30 and 32from the linearly arranged structures 30 and 32 are aligned in the samedirection as the liquid crystal molecules on the linearly arrangedstructures 30 and 32. These liquid crystal molecules are alignedcontinuously from the linearly arranged structure 30 through the gapbetween the linearly arranged structures 30 and 32 to the other linearlyarranged structures 32, so that the finger trace is left for a longtime.

In the case where the image display screen is pressed by finger in FIGS.99 and 100, on the other hand, as in the case of FIG. 102, a part 16 mof the liquid crystal molecules on the linearly arranged structures 30and 32 is pushed out toward the gap between the linearly arrangedstructures 30 and 32 into a position parallel to the linearly arrangedstructures 30 and 32. In this case, however, the liquid crystalmolecules on the linearly arranged structures 30 and 32 of the twosubstrates are aligned in opposite directions.

Therefore, the liquid crystal molecules 16 m that have been pushed outare aligned in the same direction as the liquid crystal molecules on thelinearly arranged structures of one substrate, but in the directionopposite to the liquid crystal molecules on the linearly arrangedstructures of the other substrate and fail to be continuously alignedwith the liquid crystal molecules on the other linearly arrangedstructures. Adjacent liquid crystal molecules must be continuouslyaligned, and therefore the liquid crystal molecules 16 m pushed out tendto rotate in the direction perpendicular to the linearly arrangedstructures 30 and 32 as indicated by an arrow. As a result, the fingertrace disappears within a short time

FIGS. 103 and 104 are view showing an example of the boundary formingmeans 86 of FIG. 99. The linearly arranged structures 30 of the uppersubstrate are projections. As to the linearly arranged structures 30 ofthe upper substrate 12, the means 86 for forming the boundary ofalignment of second type (II) includes a small projection 86 a arrangedon the lower substrate 14. The linearly arranged structures 32 of thelower substrate 14 are projections with regard to the linearly arrangedstructures 32 of the lower substrate 14, the means 86 for forming theboundary of alignment of second type (II) includes a small projection 86b arranged on the upper substrate 12. The small projection 86 a and thesmall projection 86 b are arranged on a line perpendicular to thelinearly arranged structures 30 and 32.

FIGS. 105 and 106 are views showing an example of the boundary formingmeans 88 of FIG. 100. The linearly arranged structures 30 of the uppersubstrate are projections. With regard to the linearly arrangedstructure 30 of the upper substrate 12, the means 88 for forming theboundary of alignment of first type (I) includes a small projection 88 aarranged on the upper substrate 12. The linearly arranged structure 32of the lower substrate 14 is a projection, and with regard to thelinearly arranged structure 32 of the lower substrate 14, the means 88for forming the boundary of alignment of first type (I) includes a smallprojection 88 b arranged on the lower substrate 14. The small projection88 a and the small projection 88 b are arranged on a line perpendicularto the linearly arranged structures 30 and 32. In FIGS. 103 to 106, thesmall projections 86 a and 86 b are longer than the width of thelinearly arranged structures 30 and 32 and extend in the direction atright angles to the linearly arranged structures 30 and 32. The width ofthe linearly arranged structures 30 and 32, for example, is 10 μm andthe height thereof is 1.5 μm. The width of the small projections 86 aand 86 b is 10 μm, the height thereof is 1.5 μm and the length thereofis 14 μm. The small projections 86 a and 86 b can be formed of adielectric material.

FIG. 107 is a view showing an example of the boundary forming means 86of FIG. 99. The linearly arranged structure 30 of the upper substrate isa projection, and with regard to the linearly arranged structure 30 ofthe upper substrate 12, the means 86 for forming the boundary ofalignment of first type includes a small slit 86 c formed in theelectrode of the lower substrate 14. The linearly arranged structure 32of the lower substrate 14 is a projection, and with regard to thelinearly arranged structure 32 of the lower substrate, the means 86 forforming the boundary of alignment of second type includes a small slit86 d formed in the electrode of the upper substrate 12. The small slit86 c and the small slit 86 d are arranged on a line perpendicular to thelinearly arranged structures 30 and 32.

FIG. 108 is a view showing an example of the means 88 of FIG. 100. Thelinearly arranged structure 30 of the upper substrate is a projection,and the means 88 for forming the boundary of alignment of second type onthe linearly arranged structure of the upper substrate 12 includes asmall slit 88 c formed in the upper substrate 12. The linearly arrangedstructure 32 of the lower substrate 14 is a projection, and the means 88for forming the boundary of alignment of second type on the linearlyarranged structure 32 of the lower substrate 14 includes a small slit 88d formed in the lower substrate 14. The small slit 88 c and the smallslit 88 d are arranged on a line perpendicular to the linearly arrangedstructures 30 and 32. In FIGS. 107 and 108, the small slits 88 c, 88 dare longer than the width of the linear wall structure 30, 32 and extendin the direction at right angles to the linearly arranged structures 30and 32.

In FIGS. 99 to 108, projections are shown as the linearly arrangedstructures 30 and 32. As an alternative, slits may of course be used asthe linearly arranged structures 30 and 32. In this case too, smallprojections or small slits can be used as the means 86 and 88. Also, thetwo means 86 including the upper substrate and the lower substrate maybe a combination of a small projection and a small slit, and the twomeans 88 including the upper substrate and the lower substrate may be acombination of a small projection and a small slit. In this way,according to this embodiment, a liquid crystal display apparatus havinga high shock resistance is obtained.

FIG. 109 is a view showing the linearly arranged structures of a liquidcrystal display apparatus according to the tenth embodiment of theinvention. FIG. 110 is a cross-sectional view of the liquid crystaldisplay apparatus of FIG. 109. Also in this case, as in the precedingembodiment, the liquid crystal display apparatus comprises a pair ofsubstrates 12 and 14, a liquid crystal having a negative anisotropy ofits dielectric constant and inserted between the pair of the substrates12 and 14, linearly arranged structures (such as projections 30 and 32or slits 44 and 46) arranged on each of the pair of the substrates 12and 14, respectively, for controlling the alignment of the liquidcrystal 16, and polarizers (not shown) arranged on the outside of thepair of the substrates 12 and 14, respectively.

According to this embodiment, the linearly arranged structures 30 of theupper substrate 12 are a projections 30, and the linearly arrangedstructures 32 of the lower substrate 14 are projections 32. Auxiliarywall structures 90 are arranged on the lower substrate 14 between thelinearly arranged structures 30 and 32 of the pair of the substrates 12and 14, as viewed in the direction normal to the pair of the substrates12 and 14. The auxiliary wall structures 90 are arranged as rhombicslits. The auxiliary wall structures 90 are long in the directionperpendicular to the linearly arranged structures 30 and 32, andarranged at predetermined pitches (5 to 50 μm) along the linearlyarranged structures 30 and 32.

FIG. 111 is a view showing a modification of the liquid crystal displayapparatus of FIG. 109. In this example, the linearly arranged structures30 of the upper substrate 12 are projections 30, and the linearlyarranged structures 32 of the lower substrate 14 are projections 32. Theauxiliary wall structures 90 interposed between the linearly arrangedstructures 30 and 32 of the pair of the substrates 12 and 14 arearranged as rectangular slits. The auxiliary wall structures 90 are longin the direction perpendicular to the linearly arranged structures 30and 32, and are arranged at predetermined pitches along the linearlyarranged structures 30 and 32.

FIGS. 112 and 113 are views showing a modification of the liquid crystaldisplay apparatus of FIG. 109. In this example, the linearly arrangedstructures 30 of the upper substrate 12 are projections 30, and thelinearly arranged structures 32 of the lower substrate 14 areprojections 32. The auxiliary wall structures 90 interposed between thelinearly arranged structures 30 and 32 of a pair of the substrates 12and 14 are provided as square projections. The auxiliary wall structures90 are arranged at predetermined pitches along the linearly arrangedstructures 30 and 32.

FIGS. 114 and 115 are views showing a modification of the liquid crystaldisplay apparatus of FIG. 109. In this example, the linearly arrangedstructures 30 of the upper substrate 12 are projections 30, and thelinearly arranged structures 32 of the lower substrate 14 areprojections 32. Each auxiliary wall structure 90 interposed between thelinearly arranged structures 30 and 32 of the pair of the substrates 12and 14 is arranged as a rectangular slit. The auxiliary wall structure90 is long in the direction perpendicular to the linearly arrangedstructures 30 and 32 and is arranged at predetermined pitches along thelinearly arranged structures 30 and 32.

The operation of the liquid crystal display apparatus shown in FIGS. 109to 115 will be explained. In a liquid crystal display apparatuscomprising the linearly arranged structures 30 and 32 on the pair of thesubstrates 12 and 14 for controlling alignment of the liquid crystal, norubbing is required and the visual angle characteristic is improved. Inview of the fact that the distance is large between the linearlyarranged structures 30 and 32 in cooperative relation, however, theresponse of the liquid crystal is low upon application of a voltagethereto. The provision of the auxiliary wall structures 90 between thelinearly arranged structures 30 and 32 facilitates the alignment of theliquid crystal in the gap between the linearly arranged structures 30and 32 and thus improves the response of the liquid crystal as comparedwhen the auxiliary wall structures 90 are absent.

More specifically, in the liquid crystal display apparatus comprisingthe linearly arranged structures 30 and 32 on the pair of the substrates12 and 14, the liquid crystal molecules are aligned in the directionperpendicular to the substrate surface and fall in a predetermineddirection upon application of a voltage thereto. The liquid crystalmolecules located at an intermediate position between the linearlyarranged structure 30 and 32 in cooperative relation will not lie in afixed direction but tend to lie in a random direction immediately aftervoltage application with the lapse of a predetermined time, however, themolecules lie in a predetermined direction. The result is a lowerresponse. In the presence of the auxiliary wall structure 90, the liquidcrystal molecules located intermediate between the linearly arrangedstructures 30 and 32 in cooperative relation lie in a predetermineddirection immediately after voltage application, thereby improving theresponsiveness.

FIGS. 109 to 115 show examples in which both the linearly arrangedstructures 30 and 32 are formed as projections, for which the auxiliarywall structures 90 including projections or slits are provided. Thelinearly arranged structures 30 and 32 are both formed as slits. As analternative, linearly arranged structures of one substrate are formed asprojections, and the linearly arranged structures of the other substrateformed as slits. Also in this case, the auxiliary wall structures 90 canbe configured of projections or slits. The projections and the slitshave substantially the same function and substantially the same effecton the liquid crystal alignment. The auxiliary wall structures 90,therefore, may be either projections or slits. Although no geometricrestriction exists, the rhombus produces a good result.

In the case where slits are formed as the auxiliary wall structures 90,the slit should be as long as possible and substantially as long as thegap between the linearly arranged structures 30 and 32 in the directionperpendicular to the linearly arranged structures 30 and 32 in order toheighten the effect of the slits. The slits, if lengthened in thedirection parallel to the linearly arranged structures 30 and 32, reducethe area of the electrode portion (in the case where the slit isarranged on the electrode), while if too short, makes it difficult toform the slit itself. The desirable length, therefore, is about 5 to 10μm. As to the distance between the slits, the effect of the slits isreduced if the distance are too long, while too short a distancedisturbs the orientation of the liquid crystal under the mutual effectof the slits. The distance of 5 to 30 μm is recommended.

In the case where projections are formed as the auxiliary wallstructures 90, the conditions to be met are somewhat different fromthose for the slits. First, the size of the projections should not betoo large, otherwise the transmittance of the liquid crystal displayapparatus is reduced. Too short a projection, on the other hand, makesit difficult to form the projection itself and reduces the effect at thesame time. The length of about 5 μm is desirable in the directions bothperpendicular and parallel to the linear wall structure 30, 32. As tothe distance between the projections, about 5 to 30 μm is desirable forthe same reason as in the case of the slit on the one hand and in ordernot to sacrifice the transmittance on the other.

The use of conductive projections as the auxiliary wall structures 90 ismore desirable as it can widen the distance between the projectionswithout sacrificing the transmittance. At the same time, the distancebetween the projections can be increased up to about 50 μm. For formingconductive projections, ITO is sputtered after forming the projection onthe substrate lacking the ITO electrode.

In the case where slits or projections are formed as the auxiliary wallstructures 90, the auxiliary wall structures 90 are not necessarilyarranged on both the substrates 12 and 14 but only one of them.

FIGS. 116A to 116G are views showing a method of fabricating thesubstrate 14 having the linearly arranged structures 32 and theauxiliary wall structures 90. As shown in FIG. 116A, the substrate 14formed with an ITO film is prepared first. In the case where thesubstrate 14 is a TFT substrate, the TFT and an active matrix are formedon the substrate followed by forming an ITO film. A positive resist(LC200 made by Shipley Far East) 91 is spin coated on the substrate 14at 1500 rpm for 30 seconds. The resist is not necessarily positive, butmay be negative. Further, a photosensitive resin may be used instead ofresist. The spin-coated resist 91 is prebaked at 90° C. for 20 minutes,after which the resist 91 is subjected to contact exposure through aphotomask 92 for ITO patterning (exposure time 5 seconds).

As shown in FIG. 116B, the resist 91 is developed (the development time50 seconds) with the developer MF319 of Shipley Far East, followed bytwo post-baking sessions at 120° C. for one hour and at 200° C. forforty minutes. As shown in FIG. 116C, the ITO of the substrate 14 isetched (etching time 3 minutes) using an ITO etchant (mixture solutionof iron chloride, hydrochloric acid and pure water) heated to 45° C. Asshown in FIG. 116D, the resist 91 is separated using acetone thereby toproduce a substrate 14 with ITO electrode having auxiliary wallstructures (slits) 90 patterned thereon.

The patterned ITO constitutes the pixel electrodes 22. It follows,therefore, that the auxiliary wall structures (slits) 90 are formed onthe pixel electrodes 22. The auxiliary wall structures (slits) 90 thusproduced are rectangular in shape having the longer side of 20 μm andthe shorter side of 5 μm with the longer side crossing at right anglesto the linear wall structure 32. Also, the distance between theauxiliary wall structures (slits) 90 are 10 μm in the directionperpendicular to the linearly arranged structures 32 and 20 μm in thedirection parallel to the linear wall structure 32.

As shown in FIG. 116E, the resist (LC200) 93 is spin coated in similarfashion to the preceding case on the substrate 14 patterned with the ITOelectrode thus prepared, and after exposure through a photomask 94 forprojection, the linearly arranged structures (projections) 32 areformed. In the process, the auxiliary wall structures (slits) 90 of theITO electrode are located between the linearly arranged structures 30and 32. FIG. 116F shows the linearly arranged structures (projections)30 and 32 thus formed. The linearly arranged structures (projections) 32have the width of 10 μm and the height of 1.5 μm and, when the upper andlower substrates 12 and 14 are laid one on the other, the interval ofthe linearly arranged structures 30 and 32 is 20 μm. Instead of theauxiliary wall structures (slits) 90 as in the case under consideration,the linearly arranged structures (projections) 32 can be formed first.

Then, the vertical alignment layers JALS684 (made by JSR) is spin coatedat 200 rpm for 30 seconds, followed by baking at 180° C. for one hour.One substrate is formed with a seal (XN-21F, made by Mitsui ToatsuChemical), and the other substrate is sprayed with a spacer (SP-20045,made by Sekisui Fine Chemical) of 4.5 μm. The resulting two substrates12, 14 are laid one on the other (FIG. 116G). In the last step, an emptypanel is produced by baking at 135° C. for 90 minutes. The liquidcrystal MJ961213 (made by Merck) having a negative dielectric constantanisotropy is injected into the empty panel in a vacuum environment.Then, the injection port is sealed with a sealer (30Y-228, made by ThreeBond) thereby to complete a liquid crystal panel (FIG. 116G).

In this case, the distance between the auxiliary wall structures (slits)90 are 20 μm in the direction parallel to the linearly arrangedstructures 32. By a similar fabrication method, a liquid crystal displayapparatus is prepared which has the auxiliary wall structures (slits) 90with distance of 20 μm in the direction parallel to the linearlyarranged structures 32.

FIGS. 117A to 117E are views showing another example of the method forfabricating a substrate having linearly arranged structures andauxiliary wall structures. As shown in FIG. 117A, a positive resist(LC200, made by Shipley Far East) 90 a is spin coated on the substrate14 having the ITO electrode (not shown) at 2000 rpm for 30 seconds. Theresist 90 a thus spin-coated is prebaked at 90° C. for 20 minutes,followed by contact exposure through a photomask 92 a (exposure time 5seconds).

As shown in FIG. 117B, the resist 90 a is developed with the developerMF319 of Sciplay Far East (development time 50 seconds), followed bypost-baking at 120° C. for one hour and again at 200° C. for 40 minutesto thereby form the auxiliary wall structures (projections) 90. Theseauxiliary wall structures have a size of 5 μm square, a height of 1 μmand a distance between projections of 25 μm (FIG. 117C).

As shown in FIG. 117D, the resist (LC200) 93 is spin coated in similarfashion on the substrate 14 thus prepared and, by exposure through thephotomask 94 for forming a projection, the auxiliary wall structures(projections) 90 are arranged between the linearly arranged structures30 and 32. In a similar manner, the other substrate 12 is formed, andthe upper and lower substrates are laid one on the other (FIG. 117E).The linearly arranged structures (projections) 32 have a width of 10 μm,a height of 1.5 μm, and the interval of 20 μm between the linear wallstructure 30, 32 when the upper and lower substrates 12, 14 are laid oneon the other.

According to yet another example, the auxiliary wall structures 90 areformed of conductive projections. A method of fabricating this will beexplained. As in the preceding case, auxiliary wall structures(projections) 90 are formed by use of a positive resist (LC200, made bySciplay Far East) on a pair of the substrates lacking the ITO electrode.These auxiliary wall structures (projections) 90 have a size of 5 μmsquare, a height of 1 μm, and the inter-projection distance of 25 μm inthe direction perpendicular to the linearly arranged structures 32 and50 μm in the direction parallel thereto. Then, the ITO is sputtered onthe substrate 14 having the auxiliary wall structures (projections) 90,thus forming the pixel electrodes 22 by etching. The auxiliary wallstructures (projections) 90 are covered by the ITO and formed asconductive projections. Then, the linearly arranged structures(projections) 32 are formed, and the two substrates 12 and 14 are laidone on the other. The linearly arranged structures (projections) 32 canof course be formed first.

FIG. 118 is a view showing the response of the liquid crystal displayapparatus of FIG. 111, in which the distance between the auxiliary wallstructures (slits) 90 are changed to 10, 20, 30, 50 μm while maintaininga constant width (5 μm) of the auxiliary wall structures (slits) 90. Themeasurement is taken at 25° C. The comparative example is the linearlyarranged structures 30 and 32, and reference is made to a liquid crystaldisplay apparatus having no auxiliary wall structures (slits) 90. Themeasurement shows that when the distance between the auxiliary wallstructures (slits) 90 is 10, 20, 30 μm, the response speed is smallerthan the response speed of the comparative example, while in the casewhere the distance between the auxiliary wall structures (slits) 90 are50 μm, the response speed is larger than the speed of the comparativeexample. Thus, the distance between the auxiliary wall structures(slits) 90 are desirably not more than 50 μm or, more accurately, notmore than 30 μm. Also, the transmittance is considerably reduced for thedistance between the auxiliary structures (slits) 90 of 10 μm or less.Thus the lower limit of the distance between the auxiliary wallstructures (slits) 90 is about 5 μm taking the resolution of the resistinto account. By the way, the transmittance for respective distancesbetween the auxiliary structures (slits) is as follows:

Comparative example 10 μm 20 μm 30 μm 50 μm 24.0% 22.7% 23.5% 23.8%24.2%

FIG. 119 is a view showing the response of the liquid crystal displayapparatus of FIG. 111 in which the distance between the auxiliary wallstructures (slits) 90 is kept constant (20 μm) while the width of theauxiliary wall structures (slits) 90 changed to 5, 10 and 20 μm. Thismeasurement shows that in the case where the width of the auxiliary wallstructures is 5, 10 and 20 μm, the response speed is smaller than theresponse speed of the comparative example. For a width of not less than20 μm of the auxiliary wall structures (slits) 90, the transmittance isreduced. Thus, the width of the auxiliary wall structures (slits) 90 isdesirably about 5 to 10 μm. By the way, the transmittance for each widthof the auxiliary wall structures (slits) 90 is as follows:

Comparative example 5 μm 10 μm 20 μm 24.0% 23.5% 22.7% 20.8%

FIG. 120 is a view showing the response with the distance between theauxiliary wall structure (projections) 90 are changed to 10, 20, 50 and70 μm with a fixed size (5 μm square) of the auxiliary wall structures(projections) 90 of the liquid crystal display apparatus of FIG. 112.This measurement shows that in the case where the distance between theauxiliary wall structures (projections) 90 are 70 μm, the response speedis larger than the response speed of the comparative example. Thus, thedistance between the auxiliary wall structures (projections) 90 aredesirably not more than 50 μm. When the distance between the auxiliarywall structures (projections) 90 are reduced below 10 μm, on the otherhand, the transmittance is reduced. Therefore, the lower limit of thedistance between the auxiliary structures (projections) 90 is about 5 μmconsidering the resolution of the resist. The transmittance for eachinterval of the auxiliary wall structures (projections) 90 is asfollows:

Comparative example 10 μm 20 μm 50 μm 70 μm 24.0% 22.3% 23.1% 23.8%24.2%

FIG. 121 is a view showing the response of the liquid crystal displayapparatus of FIG. 112, in which the size of the auxiliary wallstructures (projections) 90 is changed to 5 or 10 μm square with fixeddistance between the auxiliary wall structures (projections) 90 at 20μm. The measurement shows that the response speed for 5 μm in size ofthe auxiliary wall structures (projections) 90 is substantially the sameas that for 10 μm in size of the auxiliary wall structures (projections)90. When the size of the auxiliary wall structure (projections) 90 is 5μm, however, the transmittance is reduced. Desirably, therefore, thesize of the auxiliary wall structures (projections) 90 is about 5 μm.The transmittance for each size of the auxiliary wall structures(projections) 90 is as follows:

Comparative example 5 μm 10 μm 24.0% 23.1% 20.6%

FIG. 122 is a view showing a liquid crystal display apparatus accordingto the eleventh embodiment of the present invention. In this case, as inthe preceding embodiment, the liquid crystal display apparatus comprisesa pair of substrates 12 and 14, a liquid crystal 16 having a negativeanisotropy of dielectric constant and inserted between the pair of thesubstrates 12 and 14, linearly arranged structures (projections 30 and32 or the slits 44 and 46, for example) provided on each of the pair ofthe substrates 12 and 14 for controlling the alignment of the liquidcrystal 16, and polarizers 26 and 28 arranged on the outside of the pairof the substrates 12 and 14, respectively.

FIG. 122 shows one linearly arranged structure (projection) 30 of theupper substrate 12, and one linearly arranged structure (projection) 32of the lower substrate 14. Further, an auxiliary wall structure 96 isarranged between the linearly arranged structures 30 and 32 of thesubstrate pair at least as viewed along the normal to the substratepair. According to this embodiment, the auxiliary wall structure 96 isformed on the lower substrate 14 as a substantially flat band-shapedprojection 96A wider than the linearly arranged structure 32 in thedirection parallel to the linearly arranged structure 32. The linearlyarranged structure 32 is formed as a two-stage projection on theauxiliary wall structure 96. The parameter changing in one direction isthe height of the band-shaped projection 96A.

With this configuration, the liquid crystal is aligned obliquely at theside edge of the auxiliary wall structure 96. Further, in the case wheredielectric constant of the auxiliary wall structure 96 is smaller thanthe dielectric constant of the liquid crystal, the application of anelectric field causes the electric field (electric lines of force EL) tobe inclined thereby causing the liquid crystal to align obliquely due tothe difference between the dielectric constant of the auxiliary wallstructure 96 and the dielectric constant of the liquid crystal. Theinclination of the liquid crystal is restricted by the auxiliary wallstructure 96 as well as by the linearly arranged structures 32, so thatthe inclination of the liquid crystal immediately propagates through allthe pixels immediately after voltage application, thereby shortening theresponse time.

FIG. 123 is a view showing a modification of the liquid crystal displayapparatus of FIG. 122. This modification includes conductive projections96B arranged on the substrate 12 in an opposed relationship to thelinearly arranged structures 32. The parameter changing in one directionis the height of the conductive projection 96B formed in the opposedsubstrate 12. The liquid crystal is aligned obliquely at the side edgeof the conductive projections 96B. Further, in view of the shape of theconductive projections 96B, application of a voltage causes the electricfield to be inclined and the liquid crystal to be aligned obliquely. Thealignment is restricted by the auxiliary wall structures 96 as well asby the linearly arranged structures 32, and the liquid crystalinclination propagates to the whole pixels immediately after voltageapplication, thereby shortening the response time.

FIGS. 124A to 124E are views showing a method of fabricating the liquidcrystal display apparatus of FIG. 122. As shown in FIG. 124A, an ITO 22is formed on the glass substrate 14, thereby forming a film 96 a toconstitute band-shaped projections 96A of the auxiliary wall structures96. As shown in FIG. 124B, the film 96 a for projection is exposed tothe ultraviolet ray UV using a mask M, and is developed to form aband-shaped projection 96A of the auxiliary wall structure 96 (FIG.124C). As shown in FIG. 124D, a film 32 m which is to constitute thelinearly arranged structures 32 is formed and, using the mask M, thefilm 32 m of the linearly arranged structures 32 are exposed to theultraviolet ray UV and developed to form the linearly arrangedstructures 32 (FIG. 124E).

FIGS. 125A to 125E are views showing a method of fabricating the liquidcrystal display apparatus of FIG. 123. As shown in FIG. 125A, the glasssubstrate 12 is formed with a film 96 b to constitute the band-shapedprojection 96B of the auxiliary wall structures. As shown in FIG. 125B,using the mask M, the film 96 b for projection is exposed to theultraviolet ray UV and developed to form the band-shaped projection 96Bof the auxiliary wall structures (FIG. 125C). As shown in FIG. 125D, thefilm of the ITO to constitute the pixel electrodes 22 is formed by vapordeposition, and then as shown in FIG. 125E, a film to constitute thelinearly arranged structures 30 are formed.

FIG. 126 shows an example in which the linearly arranged structures ofthe lower substrate 14 are slits 46. The auxiliary wall structures 96includes conductive projections 96C formed on the opposite side of thelinearly arranged structures 46. The linearly arranged structures 46including the slits 46 develop electric lines of force expanding towardthe same slit. The electric lines of force develop in the directionexpanding toward the slit 46.

FIG. 127 shows an example in which the linear wall structure of thelower substrate 14 is the slit 46. The auxiliary wall structures 96, asin the case of FIG. 122, includes a band-shaped projection 96 formedunder the linearly arranged structures 46. The linearly arrangedstructures 46 including the slits 46 develops electric lines of force inthe direction expanded toward the slit. The electric lines of force aregenerated in the direction expanding toward the slit 46.

FIG. 128 shows an example in which the auxiliary wall structure 96includes band-shaped projections 96D, 96E formed in two stages on thelower substrate 14. The band-shaped projection 96D of the lower stage iswider than the band-shaped projection 96E of the upper stage, and thelinearly arranged structures 32 constituting the projections 32 areformed on the band-shaped projections 96E of the upper stage. In thiscase, the inclined alignment of the liquid crystal can be restricted bythe two side edges of the band-shaped projections 96D, 96E formed in twostages. In this configuration, the propagation distance of the alignmentinclination of the liquid crystal is one third instead of one half andtherefore the response time is improved considerably.

In FIG. 129, the auxiliary wall structure 96 includes a band-shapedprojection 96F which has a large thickness under the linear wallstructure 32 of the lower substrate 14 and inclines outward,progressively decreasing in thickness, away from the linearly arrangedstructures 32. Since the band-shaped projection 96F having a wide areais inclined, the direction of inclined alignment of the liquid crystalcan be restricted by the difference of the shape and the specificdielectric constant over a wide area. Further, the light leakage, whichis caused by the shape of the edge, when no voltage is applied can bereduced. The inclined structure can be formed by the reflow of aphotosensitive material.

FIG. 130 shows an example in which a corrugated projection 98 is formedon the lower substrate 14, and this projection 98 is caused to functionas the linearly arranged structures 32 and the auxiliary wall structure96. The period of the corrugation is changed, and the parameter changingin one direction is the period of corrugation. When the period ofcorrugation is long, the average force of restricting the inclinedalignment of the liquid crystal weakens. Further, the average electricfield distribution is inclined. Thus, the liquid crystal can be alignedby inclination. In this way, the inclined alignment of the liquidcrystal can be restricted in a wide area.

FIG. 131 shows an example in which a projection 97 changed in dielectricconstant is formed on the lower substrate 14, and this projection 97 iscaused to function as the linearly arranged structures 32 and theauxiliary wall structure 96. The projection 97 includes a portion wherethe specific dielectric constant is decreased from ∈1 to ∈2 to ∈3 insteps. Since the electric field inclination occurs in the area where thespecific dielectric constant changes, the inclined alignment of theliquid crystal can be restricted. The relative dielectric constant ofthe projection 97 may be changed continuously.

FIG. 132 shows an embodiment in which the pixel electrode 22 isconfigured of a conductor 99A of low resistivity and a conductor 99B ofhigh resistivity. The conductor 99A of low resistivity is narrower thanthe conductor 99B of high resistivity. The conductor 99A of lowresistivity is covered by the conductor 99B of high resistivity andlocated at the center of the conductor 99B of high resistivity. As aresult, an electric field inclination is developed as the charge spreadsfrom the conductor 99B in time due to the time constant determined bythe electrostatic capacity of the electrode 18 on the opposed substrateand the conductor 99B of high resistivity. Thus, the inclined alignmentof the liquid crystal can be restricted.

FIGS. 133A to 133C are views showing an embodiment in which anunevenness is formed at the end of the projection as the auxiliary wallstructure 96. In FIG. 133A, the projection end is formed in a triangularwave 96H as the auxiliary wall structure 96. In FIG. 133B, theprojection ends are formed as a curve 961 as the auxiliary wallstructure 96. In FIG. 133C, the projection ends are formed as arectangular wave 96J as the auxiliary wall structure 96. By forming anunevenness at the end of the projection, the orientation of the liquidcrystal can be stabilized. When the liquid crystal is aligned obliquely,the alignment tends to be parallel to the projection. In the auxiliarywall structure 96, the liquid crystal is required to be aligned in thedirection perpendicular to the projection. In the case where theprojection ends are uneven, the forces tending to align the projectionsin a position parallel to the projection offset each other, with theresult that the liquid crystal is oriented in the directionperpendicular to the projection.

FIG. 134A to FIG. 134C are views showing an embodiment in which thesection of the projection is defined as the auxiliary wall structure 96.In FIG. 134A, the section of the projection as the auxiliary wallstructure 96 is trapezoidal 96K in shape. In FIG. 134B, the section ofthe projection as the auxiliary wall structure 96 is arcuate 96L inshape. In FIG. 134C, the section of the projection as the auxiliary wallstructure 96 is curved 96M in shape. By doing so, the area for definingthe inclined orientation of the liquid crystal can be widened. Further,a steep section geometrically disturbs the liquid crystal orientationwhen no voltage is applied thereto. A smooth sectional shape can reducethe light leakage caused by the orientation defect of the edge.

A further embodiment can be configured from the embodiments explainedwith reference to FIGS. 122 to 134. For example, in the above-mentionedembodiments, the structure of restricting the inclined orientation ofthe liquid crystal is formed only on one substrate. Instead, thestructure for restricting the inclined alignment of the liquid crystalcan be formed on the two substrates. Then, a comparatively uniform cellthickness in the pixel can be secured thereby providing a uniformoptical characteristic. Further, the force for restricting the inclinedorientation of the liquid crystal is increased.

Also, when the liquid crystal is driven by the TFT, the process forprojection fabrication can be simplified by forming the projection of agate insulating film or the last protective film of silicon nitride orthe like. Addition of a chiral material to the liquid crystal canshorten the response time of the liquid crystal for a small electricfield. The twist energy of the liquid crystal can restore the liquidcrystal alignment more rapidly.

As described above, the means (auxiliary wall structure) for restrictingthe inclined alignment of a second liquid crystal, which increases orreduces the parameter in one direction from the linearly arrangedstructures, is formed between the linearly arranged structures. Thus,the direction in which the liquid crystal orientation is inclined can berestricted. As a result, the propagation rate of the direction ofinclination of the liquid crystal alignment increases during thetransition from black to white display, and therefore the response timecan be shortened, thereby greatly contributing to the displayperformance of the display apparatus involved.

As described above, according to the present invention, a liquid crystaldisplay apparatus can be fabricated which is improved in brightness andhigher in response speed. The direction of orientation of all thedomains formed on the linear wall structure can be determined and theage-based variation of the domains can be suppressed, thereby improvingthe overshoot.

1. A liquid crystal display apparatus having a plurality of pixels,comprising: a pair of substrates; a liquid crystal having a negativedielectric anisotropy inserted between the pair of substrates; first andsecond electrodes formed on the pair of substrates, respectively, afirst alignment control structure formed linearly on one of the pair ofsubstrates for controlling an alignment of the liquid crystal; and asecond alignment control structure formed linearly on the other of thepair of substrates for controlling an alignment of the liquid crystal;wherein the first and second alignment control structures are bent in azigzag fashion and extend parallel with each other; and at least one ofthe first and second alignment control structures includes a linearportion and a wide portion having a width wider than a width of thelinear portion.
 2. A liquid crystal display apparatus according to claim1, wherein each of the first and second alignment control structuresincludes a bent portion having two line segments at an angle of 90degrees to each other.
 3. A liquid crystal display apparatus accordingto claim 2, further comprising polarizers arranged in such a manner thatpolarization axes form an angle of 45 degrees to the line segments ofthe bent portion.
 4. A liquid crystal display apparatus according toclaim 1, wherein the first alignment control structure comprises aprotrusion formed on a first electrode or a slit formed in the firstelectrode, and the second alignment control structure comprises aprotrusion formed on a second electrode or a slit formed in the secondelectrode.
 5. A liquid crystal display apparatus according to claim 1,wherein four areas of alignment of liquid crystal molecules are formedby the first and second alignment control structures in one pixel.
 6. Aliquid crystal display apparatus according to claim 1, wherein each ofthe first and second alignment control structures includes the linearportion and the wide portion.
 7. A liquid crystal display apparatusaccording to claim 2, further comprising an additional structureextending from the bent portion for controlling an alignment of theliquid crystal.